Heat oven to 200C/180C fan/gas 6 and line a 12-hole muffin tin with paper cases. Beat the butter and caster sugar together until pale and fluffy.
Add the eggs and beat in for 1 min, then mix in the yogurt and vanilla extract
Combine the flour, baking powder and bicarb in a bowl with ¼ tsp fine salt, then tip this into the wet ingredients and stir in.
Finally, fold in the blueberries and divide the mixture between the muffin cases.
Bake for 15-18 mins until risen and golden, and a cocktail stick inserted into the centre comes out clean.
Cool in the tin for 10 mins, then carefully lift out onto a wire rack to finish cooling.