Preheat your oven to 350 degrees Fahrenheit.

Follow the instructions to prepare the box cake and bake it in a 13x9 baking dish. Allow it to cool completely.

For the Strawberry Filling, finely chop fresh strawberries and combine them in a large bowl with sugar and a hint of lemon juice, ensuring a thorough mix.

Create the Whipped Cream by blending heavy cream, vanilla, and powdered sugar in a spacious bowl or with a kitchen aid until stiff peaks form—usually taking 3-5 minutes.

Assemble your trifles in cocktail cups by starting with cut-out cake rounds (using small cookie cutters or squares). Place them at the cup's base, add a layer of strawberry, whipped cream, and repeat. Finish with a topping of whipped cream and garnish with extra strawberries if desired!