In a medium saucepan, combine the sliced strawberries, sugar, and lemon juice. Let it sit for about 15-20 minutes to release the juices.

In a small bowl, mix the cornstarch with 2 tablespoons of water until smooth. Add this mixture to the strawberries in the saucepan.

Cook over medium heat, stirring gently, until the mixture thickens and starts to bubble (about 5-7 minutes). Remove from heat and let it cool completely.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large mixing bowl, cream the softened butter and granulated sugar together using an electric mixer on medium speed until light and fluffy (about 4-5 minutes).

Add the eggs one at a time, mixing well after each addition. Then, mix in the vanilla extract.

Gradually add the flour mixture to the butter mixture in three parts, alternating with the milk (beginning and ending with the flour). Mix until just combined and smooth.

Divide the batter evenly between the prepared cake pans. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Let the cakes cool in the pans for 10 minutes, then turn them out onto a wire rack to cool completely.

Once the cakes are completely cool, place one layer on a serving plate. Spread a layer of strawberry filling over the first layer.

Place the second layer on top and frost the top and sides of the cake with the vanilla frosting. Decorate with whole strawberries on top and drizzle with any remaining frosting if desired. Chill for about 45 min before serving.