Preheat oven to 350°F. Line a muffin pan with cupcake liners. Set aside.
In a medium bowl, whisk together flour, baking powder, and salt.
In a large bowl, beat the butter, vanilla, and sugar until light and fluffy.
Add in the eggs, one at a time, beating well after each addition. Mix in sour cream and milk.
Fold the dry ingredients into the batter, mixing just until combined.
Using a rubber spatula, gently fold the raspberries, stirring just until combined.
Fill the cupcake liners about 3/4 of the way. Bake for 20-22 minutes or until a toothpick inserted into the center comes out clean. Allow to cool completely on a wire rack.
Make the buttercream by mixing together the butter and powdered sugar until light and fluffy. Add the melted white chocolate and mix until smooth.
Using a small knife or a piping nozzle, cut out the centers of the cupcakes. Fill in the centers with raspberry jam.
Pipe the buttercream onto cupcakes. Decorate each cupcake with a square of white chocolate, a fresh raspberry, rosemary, and sprinkles.