Easy Pineapple Rhubarb Crumble Bars Recipe

Name: Pineapple Rhubarb Crumble Bars
Prep time: 15 min
Cook time: 70 min
Total time: 85 min
Ingredients: 1½ cups whole oats; 1½ cups all-purpose flour; ½ cup packed brown sugar; ½ teaspoon baking powder; ¾ cup salted butter (melted); 3 cups rhubarb (cut into 1/4” thin slices); 2 cups fresh pineapple; ¾ cup granulated sugar; ¼ cup cornstarch; ¼ teaspoon salt

Jump to Recipe

Pineapple Rhubarb Crumble Bars combine tropical sweet pineapple with the tangy tartness of rhubarb. With a buttery oat crust, a vibrant fruit filling, and a crumbly topping – these bars are the perfect handheld treat for picnics, potlucks, or an afternoon snack with coffee.

Slices of pineapple rhubarb dream bars on parchment paper.

Table of Contents

As the summer transitions to fall, this dessert bar recipe does too. Take advantage of rhubarb season and combine it with some summer sweetness allowing you to extend the sunny months (and flavors) just a little longer.

I’ve been making variations of crumble bars for years, like our Blueberry Pie Bars. Yet this pineapple rhubarb combination is something special. They are ideal for brunch, an afternoon snack, or a dessert. Plus, these bars hold together beautifully when you cut them, which makes them perfect for sharing or packaging up as gifts.

You’ll also want to try our Strawberry Rhubarb Streusel Muffins too.

Recipe at a Glance

Simple ingredients: You probably have most of these items in your pantry already, and fresh rhubarb is easy to find in the fall.
Perfect balance of flavors: Tart rhubarb meets the sweetness of pineapple for a flavor combination that’s both unique and addictive.
Great texture: Buttery, crumbly oat crust and topping with a jammy fruit center creates the perfect bite every time. Same with our Easy Blackberry Cobbler Recipe too.
Make ahead friendly: These bars actually taste better the next day once the filling has set completely.
Feeds a crowd: One pan of rhubarb bars makes plenty for gatherings, bake sales, or meal prep desserts.
Freezer friendly: Make a double batch and freeze half for later when you need a quick dessert.

Total Time: 85 Minutes

Serves: 9-16

Ingredients and Notes

As always, the full ingredients and recipe is on the printable recipe card at the end of this post.

Whole Oats – Compared to quick oats, old-fashioned oats hold their shape much better and do not become mushy.
All-Purpose Flour
Sugar – You’ll need both brown sugar and white sugar for this recipe.
Salted Butter – Ensure it’s melted butter.
Baking Powder – Allows the crust and crumble to be little thicker and softer.
Rhubarb – You’ll need about 6 medium stalks to make 3 cups when chopped.
Pineapple – I use fresh pineapple for this recipe.
Cornstarch – This acts as a thickener.
Salt

Ingredients on a table to make pineapple rhubarb crumble bars.

How to Make Pineapple Rhubarb Crumble Bars

1 (not pictured) – Prepare Your Pan and Preheat
Preheat the oven to 350 F. Line an 8-inch square pan with parchment paper, leaving some overhang on the sides for easy removal later. Also spray with nonstick spray.

2 – Prepare the Crust Mixture
Place whole oats, flour, brown sugar, and baking powder in a medium bowl. Add melted butter and mix until it combined to coarse crumbs.

An oat crust in a baking pan for pineapple rhubarb dream bars.

3 – Form and Bake Crust
Press 2/3 of the mixture into the bottom of the prepared pan, setting the other 1/3 aside. Bake for 15 minutes; the crust will be lightly browned around the edges.

Pineapple and rhubarb chunks in a glass bowl with flour an baking powder.

4 – Prepare the Filling
In a medium bowl, combine diced rhubarb, diced pineapple, granulated sugar, cornstarch, and salt. Mix well until the sugar starts to dissolve and the fruit looks moist.

pineapple rhubarb filling for squares n a baking pan.

5 – Add Filling and Topping
Pour the rhubarb mixture over the crust and sprinkle the remaining crumble evenly on top of the fruit.

A whole baking pan with pineapple rhubarb crumble.

6 – Bake, Cool, Cut and Serve
Bake for 70 minutes, checking at the 65 minute mark. The crumb topping should be golden brown, with the filling bubbling around the edges. It takes this long because both rhubarb and pineapple have a high-water content and require a longer bake time to set properly. When cooked, allow these delicious bars to cool completely before cutting into squares using a sharp knife.

A slice of Pineapple Rhubarb Crumble Bar being lifted from a baking pan with a spatula.

What I Learned Making This Recipe

Don’t skip the cooling time: I know it’s tempting to dig in right away, but warm bars will fall apart. The filling needs time to set up completely.
Cut rhubarb evenly: Try to keep your rhubarb pieces uniform in size so they cook evenly. My stalks were extra thick, so I cut them in half vertically before cutting them into ¼ inch slices
Press the crust firmly: A well-packed bottom crust won’t get soggy and will hold together better when you cut the bars. For a crustless fall dessert try our Apple Cobbler using Cake Mix.
Check for doneness: The filling should be actively bubbling around the edges, and the top should be golden brown. If the top is browning too quickly, tent with foil for the last 10 minutes.
Use parchment paper: This makes removing the bars from the pan so much easier and ensures clean cuts.
Let the sugar work: Allowing the fruit mixture to sit for a few minutes while the crust finishes baking helps the sugar begin breaking down the fruit.

A stack of three squares of pineapple rhubarb bars.

Recipe Variations and Substitutions

Sugar variations: Swap the brown sugar for coconut sugar in the crust. You can also reduce the granulated sugar in the filling to 1/2 cup if your pineapple is very sweet.
Different fruits: Try strawberry rhubarb, apple rhubarb, or even peach rhubarb combinations. Adjust the sugar based on the sweetness of your chosen fruit. You can do the same with our Pineapple Crisp Recipe.
Add spices: A teaspoon of vanilla extract in the filling or 1/2 teaspoon of cinnamon in the crust adds extra warmth and depth.
Nuts for texture: Add 1/2 cup of chopped pecans or sliced almonds to the crumble topping for extra crunch.
Quick oats: If you only have quick oats, they’ll work fine, though the texture will be slightly less hearty.
Unsalted butter: If using unsalted butter, increase the salt in the crust mixture to 1/3 teaspoon.

How to Store Pineapple Rhubarb Crumble Bars

Refrigerator – Store in the fridge in an airtight container for 5 days.
Freezer – These bars freeze beautifully. Wrap individual bars in plastic wrap, then place them in a freezer-safe container or bag. Freeze for up to 3 months. Thaw overnight in the refrigerator or at room temperature for a few hours. You can also freeze the entire uncut slab if you prefer.

What to Serve with Rhubarb Dessert Bars

These rhubarb crumb bars are delicious on their own, warmed up or cold. Yet you can also serve them with a scoop of vanilla ice cream, a dollop of whipped cream, or a drizzle of cream cheese frosting. Some people enjoy them with a cup of hot tea or coffee for an afternoon treat.

Recipe FAQ

Can I use frozen rhubarb for crumble bars?

You can use frozen rhubarb; you will want to thaw and drain any excess water before using it, so the filling isn’t runny.

Can I use canned pineapple?

I would recommend that you stick with fresh pineapple for this recipe. Aside from the taste of fresh being tangier and brighter, canned pineapple is sweeter from being packed in syrup, softer, and has more moisture than fresh. Substituting would require some adjustments to the original recipe.

Can I make rhubarb crumble bars ahead of time?

Absolutely! These bars actually taste better the next day once the flavors have had time to meld. Make them up to 2 days ahead and store them covered at room temperature, or up to 5 days ahead in the refrigerator. Our Rhubarb Streusel Muffins are great for school lunches.

Do pineapple and rhubarb go together?

Yes, absolutely! The sweetness of the pineapple and bitterness of rhubarb makes for a dessert that has a balanced flavour. This is especially true for those that usually don’t like the tartness of rhubarb.

More Dessert Bar Recipes

If you’ve tried this Rhubarb Pineapple Crumble Bars Recipe please let me know how it went in the comments below. Finally, consider leaving a 🌟 star rating while you’re here. Thanks!

A slice of Pineapple Rhubarb squares being lifted from a baking pan with a spatula.

Pineapple Rhubarb Crumble Bars

Treat yourself to Pineapple Rhubarb Crumble Bars, combining the tangy taste of rhubarb with sweet pineapple goodness.

5 from 1 vote

Print Pin

Prep Time: 15

Cook Time: 1 10

Total Time: 1 25

Servings: squares

Course: Dessert

Cuisine: American

Author: Tammi

Ingredients

Crust

1½ cups whole oats
1½ cups all-purpose flour
½ cup packed brown sugar
½ teaspoon baking powder
¾ cup salted butter (melted)

Filling

3 cups rhubarb (cut into 1/4” thin slices)
2 cups fresh pineapple
¾ cup granulated sugar
¼ cup cornstarch
¼ teaspoon salt

Instructions

Preheat the oven to 350 F. Line an 8-inch square pan with parchment paper and spray with nonstick spray.
Place whole oats, flour, brown sugar, and baking powder in a medium bowl. Add melted butter and mix until well combined and crumbly.
Press 2/3 of the mixture into the bottom of the pan. Bake for 15 minutes; the crust will be lightly browned around the edges.
In a medium bowl, combine diced rhubarb, diced pineapple, granulated sugar, cornstarch, and salt. Mix well until the sugar starts to dissolve and the fruit looks moist.
Pour the fruit mixture over the crust and sprinkle the remaining crumble evenly on top of the fruit.
Bake for 70 minutes. The bars should be golden brown, with the filling bubbling around the edges. Let cool and cut into squares.
Let the bars cool completely before cutting into squares.

Notes

You can use frozen rhubarb; you will want to thaw and drain any excess water before using it, so the filling isn’t runny.

Store cooked bars in the fridge in an airtight container for 5 days. Can be frozen for 3 months; separate the layers with parchment paper for easy removal.

Tried this recipe?Tag @MyOrganizedChaosBlog so I can share!