Preheat your oven to 350°F (175°C) and line a cupcake tin with liners.
In a mixing bowl, combine flour, baking powder, and salt. In another bowl, cream the softened butter and sugar until light and fluffy. Beat in the egg, vanilla extract, milk, and strawberry puree. Gradually add the dry ingredients and mix until combined.
Divide the batter evenly among the cupcake liners and bake for 15 minutes or until a toothpick comes out clean. Allow to cool completely.
For the buttercream, beat the softened butter until creamy, then gradually add the powdered sugar, strawberry puree, vanilla extract, and salt. Mix until smooth and fluffy.
Pipe the strawberry buttercream onto the cooled cupcakes and enjoy!
Notes
You can use fresh strawberries for the puree or store-bought. For a stronger strawberry flavor, add more strawberry puree to the buttercream.