Step 1

Preheat a convection oven to 375 degrees F (190 degrees C). Lightly grease a 9x13-inch baking dish.

Step 2

Pour sliced strawberries for filling into a bowl. Add sugar, cornstarch, and cinnamon; mix to combine.

Step 3

Mix flour, both sugars, oats, 1/2 teaspoon cinnamon, and salt for topping in another bowl until combined. Add 1/4 cup melted butter and stir until thoroughly combined and crumbly.

Step 4

Combine remaining 1/4 cup melted butter, milk, and remaining 1 teaspoon cinnamon in a small dish.

Step 5

Pour the strawberry mixture into the prepared baking dish and sprinkle crumb mixture over top. Pour butter mixture over the crumb topping.

Step 6

Bake in the preheated oven on the convection setting until topping is golden brown, 30 to 40 minutes. Serve warm or at room temperature.