Preheat the oven to 350 degrees or as indicated on the box cake mix.

Spray 4 9-inch round cake pans with baking spray or grease with butter and flour. Cut 4 rounds of parchment paper and place into the cake pan. Spray or grease parchment paper.

Prepare cake mix as indicated on the back of the box, adding in vanilla extract. Divide cake batter evenly between the pans.

Bake cakes in the preheated oven according to package directions, at least 30 minutes. When the cake just begins to pull away from the edges of the pan and springs back when touched, it is done.

Let cakes cool in the pans for 10 minutes then turn out onto wire cooling racks, the side with the parchment paper onto the rack. Cool to room temperature, then refrigerate for 1 hour.

Meanwhile, cut the tops off the strawberries and slice them into thin wedges. Reserve 4-5 whole strawberries to place on top of the cake. Add to a large bowl and sprinkle sugar on top, tossing to coat.

When you are ready to assemble the cakes, remove from the refrigerator and pull off the parchment paper, returning the cakes to the wire cooling rack.

Combine the heavy whipping cream, sugar and vanilla extract in a bowl or in the bowl of a stand mixer and whip on medium high to high speed until soft peaks form.

Use a sharp knife to level off any uneven layers of the cakes.

Place the first cake onto the serving dish and top with a dollop of whipped cream. Spread the whipped cream to the edges of the cake. Use approximately ¼ of the whipped cream. Arrange a thin layer on strawberries on top, using about ⅓ of the mixture.

Repeat with the second and third layers of the cake and strawberries. Place the final layer of the cake on top and spread the whipped cream over it, either smoothing it or leaving it shaped into a soft peaks. Place the reserved whole strawberries on top.

Refrigerate until ready to serve, then slice into pieces.