Preheat the oven to the temperature required according to the directions on the cake mix box. Grease and line the bottom of two 9-inch cake tins with baking paper.
Tip the cake mix into a large bowl and add the eggs, vegetable oil and water following the directions on the box for the quantities needed and mixing directions.
Divide the batter between the cake pans and bake for the time given on the cake mix box.
Tip the cake layers out onto wire racks, peel the baking paper off and set aside to cool completely.
For the filling:
Let the strawberry ice cream soften for a few minutes before scooping it out into a large bowl. Use a wooden spoon to beat the ice cream until you get a buttercream-like texture. Add the diced strawberries and fold together.
Line a tall 9-inch springform cake pan with plastic wrap, allowing a few inches to overhang on the outside of the cake pan. Place the first cooled cake layer in the pan. Spread the softened strawberry ice cream in an even layer over the whole thing. Place the second cake layer on top. Cover with the overhanging plastic wrap and freeze for 3-4 hours until firm.
Pulse the freeze-dried strawberries and vanilla wafers together in a food processor until broken down into a breadcrumb-like texture.
Remove the cake from the freezer and from the springform pan. Peel away the plastic wrap carefully.
Use a metal offset spatula to spread the vanilla frosting in a thin, even layer over the top and sides of the cake.
Quickly press your strawberry-vanilla wafer powder over the top and sides of the cake.
Pipe 6-8 peaks of vanilla frosting onto the top of the cake using a piping bag fitted with a wide star tip. Top each of these with a halved strawberry.
Line your pan with plastic wrap to help unmold it later.