Easy Rhubarb Crisp

Step 1
Gather all ingredients.

Step 2
Preheat the oven to 350 degrees F (175 degrees C). Grease a 9×13-inch baking dish.

Step 3
Mix flour, brown sugar, oats, butter, and cinnamon together in a bowl until crumbly. Press 1/2 of the oat mixture into the bottom of prepared baking dish.

Step 4
Sprinkle rhubarb over oat mixture.

Step 5
Combine white sugar, water, cornstarch, and vanilla in a saucepan over medium heat; cook and stir until thick and clear, about 5 minutes.

Step 6
Pour sugar mixture over rhubarb.

Step 7
Sprinkle remaining oat mixture over rhubarb.

Step 8
Bake in the preheated oven until the crisp is lightly brown and bubbling, about 1 hour.