Preheat oven to 350°F and line an 8x8-inch baking pan with parchment paper. In a large bowl, mix strawberry cake mix, eggs, vegetable oil, and vanilla extract until combined. Press thick batter evenly into the prepared pan. Bake for 18–22 minutes until set in the center. Allow brownies to cool completely. In a mixing bowl, beat softened butter until smooth. Gradually add powdered sugar, then mix in heavy cream and vanilla extract until fluffy. Spread frosting evenly over cooled brownies. In a separate bowl, mix crushed cookies, strawberry gelatin powder, and melted butter until crumbly. Sprinkle crumble topping evenly over frosting. Chill for 30 minutes before slicing and serving.