Make vanilla cake according to recipe. Cool completely. Slice cakes in half lengthwise to create 4 layers.
Whip heavy cream with vanilla and powdered sugar until stiff peaks form. Remove half of the cream and set aside. Stir diced strawberries into the remaining cream.
Place one layer of cake onto a serving platter. Spread 1/3 of the strawberries and cream filling overtop. Add another layer of cake and continue layering until all 4 layers are in tact. If filling looks like it's being pushed out from the sides of the cake, simply scrape the edges to even everything out. Frost the entire cake with remaining plain whipped cream. Top with sliced strawberries as a garnish.
Refrigerate 4 hours to overnight to set completely (so it will cut nicely). Slice and serve.