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

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.

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.

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.

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.

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