Preheat oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.
In a bowl, whisk together flour, baking powder, and salt.
In another bowl, cream butter and sugar until light and fluffy. Beat in eggs one at a time, then mix in vanilla.
Add dry ingredients to wet mixture in batches, alternating with milk. Mix until just combined.
Fill each cupcake liner halfway, add a small spoon of raspberry puree, then top with more batter. Swirl gently with a toothpick.
Bake 18–20 minutes or until a toothpick inserted in the center comes out clean. Cool completely before serving.