Preheat your oven to 180°C (350°F) or 160°C (fan). Line a mini muffin tin with 12 paper cases or grease the tin lightly.
In a bowl, beat the butter and sugar together until pale and fluffy. Use an electric mixer or a wooden spoon for the best results.
Beat in the eggs one at a time, mixing well after each addition. Add a tablespoon of flour if the mixture starts to curdle.
Sift the self-raising flour and baking powder into the bowl. Gently fold into the mixture using a spatula or spoon. If the batter feels too thick, add a tablespoon of milk.
Spoon the batter evenly into the prepared mini muffin cases, filling each about ¾ full to allow room for rising. Sprinkle white chocolate chips on the muffins.
Bake in the preheated oven for 12–15 minutes, or until the muffins are golden and a skewer inserted into the center comes out clean. Remove from the oven and let them cool in the tin for 5 minutes before transferring to a wire rack to cool completely.
Once the muffins are completely cool, optionally use a sharp knife to cut a small circular hole in the top of each muffin. Fill each hole with a little jam and a dollop of whipped cream or buttercream.
Dust the tops with icing sugar for a simple and elegant finish.