Preheat oven to 350 degrees F. Line 2 cupcake tins with paper liners, set aside.

In a large bowl, whisk or sift together the flour, baking powder, and salt. Set aside.

Cream together the sugar and butter with an electric mixer until light and fluffy, about 5 minutes. Beat in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract. Add the dry ingredients along with the buttermilk, alternating between the two, starting and ending with the dry ingredients. So a little dry, buttermilk, dry, buttermilk, dry once again. Make sure to only mix until just incorporated. You don't want to over-mix the batter at this point. Divide the batter evenly among the prepared cupcake tins, filling just a little over halfway up each. Bake until golden brown and a toothpick inserted in the middle comes out clean, about 15 to 18 minutes. Remove from oven and let cool completely on a wire rack.

To make the buttercream, beat the butter in an electric mixer on high until light and fluffy, about 3 minutes. Add the powdered sugar, salt, vanilla and frozen strawberry purée and beat until well combined and fluffy. (To make the frozen strawberry purée, let a bag of frozen strawberries thaw in the fridge overnight and then purée about 1/4 of them until smooth. Then measure out 3 tablespoons). If the frosting is too thick, try adding a bit of cream or mill, a little bit at a time and mix until desired consistency is reached.

Once cupcakes are completely cooled, frost each and shape with an offset spatula. Roll the edges of the cupcake in sprinkles. Serve immediately or place in the fridge until ready to eat. Just let them come to room temperature before serving.