Preheat your oven to 350°F (175°C).
Grease and flour two 9-inch round cake pans.
In a bowl, combine sliced strawberries and granulated sugar; set aside.
In a separate bowl, whisk together flour, baking powder, and salt.
In a large bowl, cream the butter and sugar until light and fluffy.
Add milk and vanilla to the butter mixture, mixing well.
Gradually add the dry ingredients to the wet ingredients until just combined.
Divide the batter evenly between the prepared pans.
Bake for 25-30 minutes or until a toothpick comes out clean.
Let cakes cool for 10 minutes before transferring them to wire racks.