Preheat oven to 200C/180C Fan/Gas 6. Line a 6 hole muffin tin.
In a large bowl, or in the bowl of a stand mixer, combine the butter and sugar until light and totally combined (at least 3-5 minutes). Add the eggs and vanilla and mix again.
Add the flour and fold gently using a spatula or spoon. Add the milk to mix.
Scoop the batter to fill 6 cupcake liners - no more than 2/3 full. Bake for 15-20 minutes, until golden and a skewer inserted comes out clean. Let cool on a wire rack.
Once cool, make the frosting. Combine the butter and half the icing sugar using an electric mixer on high. Add the raspberries and remaining icing sugar, plus the food colour if using. Add icing sugar or milk if consistency isn't as you'd like. Spread over the cupcakes and top with sprinkles/raspberries/decorations of choice!