Heat the oven to 200C/180C fan/gas 6 and line a 12-hole muffin tin with paper cases.

Beat the butter and sugars together for 5 mins until pale and fluffy. Add the eggs gradually and beat in until combined. Mix in the yogurt, vanilla and milk.

Fold in the flour, baking powder and a pinch of fine salt until you have a smooth batter. Finally, fold in 150g of the blackberries and fill the muffin cases 3/4 full. Poke 2 blackberries (or 4 halves) into the top of each muffin, so that they are sticking out slightly. Bake for 8 mins, then reduce the oven to 180C/160C fan/gas 4 and bake for 20-25 mins more until risen and golden, and a cocktail stick inserted into the centre comes out clean.