Apple Rhubarb Crisp

Fruit crisps are family-favorite desserts, and my girls wait in anticipation 'til summer for the apples on our tree to reach their zenith, the blackberries on our road to achieve peak sweetness, and our neighbors' peaches to (see my gluten free apple crisp, gluten free blackberry crisp, and gluten free peach crisp recipes to make the most of summer's bounty!).

I feel like there are endless iterations of fruit crisp - my any fruit crisp post captures this philosophy well! - and I'm always looking for more ways to experiment. Apples and rhubarb are a natural pairing, with the inherent sweetness of the apples balancing the tartness of the rhubarb (my gluten free apple and rhubarb cake also carries out this combination perfectly).

This is a simple recipe, nothing fussy, no fancy ingredients, just whole grain flour, oats, rhubarb, apples, butter, sugar, and a touch of ginger. The minimal ingredients allow the flavors of the filling to shine through; you'll actually be able to taste the rhubarb+apples without them being oversugared or overshadowed by too much spice. Make sure to serve this warm with vanilla ice cream for a true summer treat

Lots to Love

• A forgiving recipe. You can swap ingredients in and out here, depending on your tastes and dietary needs, and it will always taste delicious.
• Rustic and always welcome. Crisps and crumbles are so homey and humble - my kind of bake! You won't need much time or effort to pull this off and everyone always seems super happy to see a crisp as the dessert offering.
• Celebrates summer. I love easy fruit desserts in summer; even when it's hot outside, they justify turning on the oven! Happily, they don't take overlong to bake and are such a seasonal favorite, no matter what fruit you use.

Ingredients Needed

Here's everything that goes into this rhubarb apple crisp. Make sure to scroll down to my recipe card at the bottom of this post for the full ingredient amounts and instructions!

• Oats - For all crisp toppings, I use "old-fashioned" rolled oats to give texture and chew to the crisp.
• Flour - For a gluten-free crisp, use oat flour or brown rice flour. If you don't need to keep gluten-free, try a whole grain flour like whole wheat pastry flour or spelt flour, or use all-purpose flour.
• Granulated sugar - Needed both for the topping and the filling. Sometimes I like to use brown sugar in the topping rather than granulated sugar.
• Baking powder
• Ginger - I use ground ginger; grated fresh ginger would add even more flavor.
• Butter - Unsalted butter is best. For a dairy-free option, swap non-dairy butter or melted coconut oil.
• Rhubarb - Choose firm, unblemished stalks of rhubarb. Ripe rhubarb can be green, pink, or red.
• Apples - I use whatever I have handy. Gravensteins are lovely when they ripen on our tree, and some may prefer Granny Smith apples for a tarter bite. Your choice.
• Salt - Fine sea salt or table salt.

Crisp or Crumble?

When I developed this recipe, I originally meant to make an apple rhubarb crumble, but I just ... can't ... skip those toasty oats in the topping! Thus I pivoted and made it into an apple rhubarb crisp.

What's the difference? Well, both a crisp and a crumble have a layer of fruit topped by a buttery crust. However, a crisp most often incorporates oats (and/or nuts) into the topping, while a crumble is a combination of flour and butter - and no oats. Both are delicious, but I'll admit I'm partial to crisps!

Tips & Recipe Notes

• Cut the filling ingredients uniformly. While rhubarb and apples are obviously different produce items, to help the filling cook at the same rate, try to cut them about the same size. I like 1-inch pieces, but feel free to go larger or smaller as you prefer. Just try to keep them around the same size!
• Chill the topping. I always place my bowl of topping in the fridge to chill while I make the filling. This lets the butter firm up slightly, making for a crisper topping later. And it performs double duty by allowing the flour to hydrate, which also makes for a better finished result.
• Rest after baking. Let the crisp sit for at least 15 minutes so that the filling sets up a bit. Or just leave it at room temperature until ready to serve.
• Enjoy at any temperature. Crisp tastes amazing warm, at room temperature, or even straight out of the fridge!
• Oat and oat flour substitute - Substitute almond flour and almonds for the oat flour and oats. Feel free to use all-purpose flour if you prefer.
• To serve: Vanilla ice cream is my favorite finish to crisp, and whipped cream or a drizzle of salted caramel sauce is also lovely. Or enjoy crisp at breakfast with a big spoonful of regular or Greek yogurt.

To Store and Reheat

• Counter - Cover the crisp with a piece of foil and store it on the counter for up to 2 days.
• Fridge - Place the leftover cooled crisp in an airtight container or leave it in the baking pan, cover it tightly, and store it in the fridge for up to 5 days. 
• Freezer - Freeze the whole crisp by wrapping the baked and cooled crisp in a layer of plastic and a layer of foil, then store it in the freezer for up to one month. You can reheat the crisp directly from the freezer: Remove the plastic and foil, and place it in a preheated 350˚F oven and heat until it's hot all the way through.
• To Reheat - Enjoy your crisp cold, or warm it in a preheated 350˚F oven until the topping is crisp and the filling is bubbly. Or heat portions in the microwave in 30-second increments until warm.