In a small saucepan over medium heat combine the strawberries, sugar, and cornstarch.
Mix together well and continue stirring and lightly mashing the berries to break them down a little more as the mixture heats and begins to bubble.
Cook for approximately 10-15 minutes, until the strawberry mixture begins to thicken. You’ll know it is ready when the strawberry filling coats the spoon and slowly drips off of it.
Remove the strawberry filling from the heat, stir in the lemon juice, and let cool completely. For best results let it cool to room temperature then put it in an airtight container and place it in the refrigerator overnight.
Cut the prepared angel food cake in half horizontally. Set the top half to the side and place the bottom half on your cake plate.
In the bottom half create a groove for the filling by cutting a circle around the inside of the cake near the center hole leaving approximately 1 inch - 1 1/2 inch between the cake hole and the inside of your circle.
Then cut around the outer edge of the cake leaving approximately 1 - 1 1/2 inch between the outer edge of the cake and the outer edge of your circle.
Gently remove the cake between your two cuts, making sure to leave some at the bottom, to create a groove for the filling.
Use a spoon to fill the groove with the chilled strawberry filling. Fill until it is level with the top of the groove and then put the top layer of cake back on and place in the refrigerator while you make the stabilized whipped cream frosting.
Once the whipped cream frosting is ready remove the cake from the refrigerator and use a spatula to frost the entire cake.
Decorate with fresh strawberries and serve.