Preheat your oven to 350°F and prepare a muffin tin with cupcake liners.

In a large bowl, beat the softened butter and sugar together until airy and pale.

Incorporate the eggs one at a time, blending each fully before adding the next.

Mix in the vanilla extract.

In another bowl, combine the flour, baking powder, and salt.

Gradually mix the dry blend into the buttery mixture, alternating with the milk, until just combined.

In a small dish, lightly crush the raspberries and mix in the raspberry preserves.

Fill each cupcake liner about two-thirds full with batter.

Add a dollop of the raspberry mixture into the center of each cupcake and swirl gently with a skewer.

Bake for 18-20 minutes, or until a toothpick comes out clean.

Let cool in the tin for 5 minutes before transferring to a wire rack to cool completely.