Strawberry Rhubarb Buckle

Preheat the oven to 350 degrees F (175 degrees C).

Make filling: Combine rhubarb, strawberries, sugar, lemon juice, and 1 tablespoon water in a large saucepan. Cook covered, stirring occasionally, over medium-low heat until mixture begins to boil, about 5 minutes. Reduce heat to low.

Stir together remaining 2 tablespoons water and cornstarch in a small bowl until smooth. Add to the saucepan and continue cooking until fruit mixture begins to thicken, about 2 minutes. Remove from heat and set aside to cool.

Grease a 9-inch deep-dish pie pan with nonstick cooking spray and place on a baking sheet. Set aside.

Make batter: Beat together butter and sugar with an electric mixer in a large bowl until light and fluffy. Beat in yogurt, egg, and vanilla until well combined. Add flour, baking powder, baking soda, and salt; mix until batter is just combined.

Spread 2/3 of the batter into the prepared pan. Pour filling on top of batter. Spread remaining 1/3 of the batter in small mounds atop filling. Set aside.

Make topping: Combine flour, brown sugar, and butter in a small bowl. Mix with a fork, pastry blender, or your hands until topping resembles coarse crumbs. Sprinkle evenly over the top of batter and filling.

Bake in the preheated oven until topping is nicely browned, about 35 minutes.