Preheat the oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.
In a medium bowl, whisk together flour, baking powder, and salt; set aside.
In a large bowl, beat butter and sugar until light and fluffy.
Add eggs one at a time, beating well after each, then mix in vanilla extract.
Alternately add dry ingredients and milk, starting and ending with dry ingredients, mixing until just combined.
Fold in strawberry puree gently until evenly incorporated.
Divide batter evenly among cupcake liners, filling each about 2/3 full.
Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean.
Let cupcakes cool completely on a wire rack.
For the buttercream, beat butter until creamy, then gradually add powdered sugar.
Mix in strawberry puree, vanilla, and a pinch of salt; beat until smooth and fluffy.
Frost cooled cupcakes with strawberry buttercream and decorate as desired.
