Preheat the oven to 350°F (175°C). In a large mixing bowl, combine the gluten-free flour, sugar, baking powder, and salt. Mix well. Add the butter, milk, eggs, and vanilla extract. Beat on medium speed for 2 minutes until smooth. Gently fold in the sliced strawberries.

Pour the batter into a prepared 9-inch round cake pan and smooth the top. Bake for 30 to 35 minutes, or until a toothpick inserted comes out clean. Allow to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

Prepare the strawberry filling by slicing remaining strawberries and optionally tossing with sugar. For frosting, beat heavy cream with sugar and vanilla until soft peaks form, or beat cream cheese with butter and powdered sugar until smooth.

Once the cake is cool, slice it in half horizontally. Spread frosting on the bottom layer, add strawberry filling, place the second layer on top, and frost the top and sides of the cake. Decorate with fresh strawberries or powdered sugar if desired.