Add the cup of strawberries into a blender or processor and puree until smooth. Add the puree to a small saucepan on the stovetop and cook until the amount of puree simmers down to half 1/2 cup, about 20-25 minutes. Set the reduced puree aside to cool completely.
Make the Cake
Preheat oven to 350 degrees. Grease 2 9-inch round cake pans with shortening and then dust with flour.
In a large bowl, combine the cake mix, butter, eggs and milk. Mix for 2-3 minutes at medium speed. Bake for 22-30 minutes or until the center of the cake bounces back when you touch it.
Allow the cakes to cool for 10 minutes in the pans, then turn them out onto wire racks to cool completely.
Prepare the Strawberry Decorations
Prepare the garnish strawberries by making a small slice, several times, around the base of the strawberry. Using the knife, push the slice outwards to create a petal. Proceed to create slices, going up towards the tip of the strawberry and push them outwards as well. Remove the greens and set aside.
Preparing the Frosting
In a large mixing bowl, combine the butter and powdered sugar. Mix well until nice and creamy. Add in the cooled puree and mix well.
Assemble the Cake
Once the cake is done cooling, place one cake layer on a cake plate. Frost the top. Place the second cake layer on the first layer. Frost the top and sides of the cake with the remaining frosting.
Garnish the top with your strawberry roses.
Store at room temperature for 24 hours, then refrigerate any leftovers in an airtight container.
The calories shown are based on the cake being cut into 15 pieces (using all of the frosting), with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate.