Ingredients
Equipment
Method
Prepare and preheat
- Preheat the oven to 375°F and butter a 9x13-inch baking dish. This prevents sticking so the crisp lifts out cleanly.
Make the rhubarb filling
- Combine rhubarb, sugar, all-purpose flour, and orange zest, then spread the mixture in the prepared baking dish. Cover the surface evenly so the filling bakes into syrup.
Make the oat topping
- Mix old-fashioned oats, all-purpose flour, brown sugar, cinnamon, and salt in a bowl. Stir until the dry ingredients are evenly colored.
- Cut in cold butter until the mixture resembles coarse crumbs. Keep the butter cold so the topping turns crisp and golden.
Assemble and bake
- Spread the oat topping evenly over the rhubarb mixture. Aim for an even layer so it browns uniformly.
- Bake for 40-45 minutes at 375°F until the topping is golden brown and the filling is bubbling. Look for active bubbling at the edges and set crumbs across the top.
Cool and serve
- Cool for 15 minutes before serving. This short rest thickens the syrup so each spoonful holds its shape.
- Serve with vanilla ice cream or whipped cream. Add right before eating for creamy contrast to the crisp top.
Notes
For the best texture, use fresh rhubarb and keep the butter cold until it’s cut into coarse crumbs—warm butter can make the topping dense. Store leftovers in the refrigerator up to 4 days in an airtight container; reheat individual portions in the oven at 350°F until warmed through. Freezing is not recommended because the rhubarb can soften after thawing. If you want a lighter option, replace half the sugar in the filling with a 1:1 baking sugar substitute and taste the syrup for balance.