Step 1

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch sheet pan.

Step 2

Wash and hull strawberries. Puree strawberries in a blender. You should have 1 3/4 cups strawberry puree. Set aside 1/2 cup strawberry puree for the frosting.

Step 3

Combine cake mix, 1 1/4 cups strawberry puree, eggs, oil, and gelatin in a bowl. Beat using an electric mixer until thoroughly combined. Pour batter into the prepared sheet pan and smooth out the top.

Step 4

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 35 to 45 minutes. Remove from oven and cool completely on a wire rack.

Step 5

Combine butter and cream cheese in a bowl and beat with an electric mixer until smooth. Add 1/2 cup strawberry puree, powdered sugar, and vanilla extract, and beat until frosting is smooth.

Step 6

Frost cooled cake with strawberry frosting. Keep refrigerated until serving.