Upside down lemon and blueberry cakes

2/3 cup lemon butter
250g blueberries
125g butter, at room temperature
1/2 cup caster sugar
1 tsp vanilla extract
2 eggs
1 cup SR flour, sifted
1/2 cup plain flour, sifted
cream or custard to serve

1. Preheat oven to 180C. Line bases of 6 large muffin tins with baking paper. Put 2 tsp of lemon butter in each hole and top with blueberries.
2. Beat butter, sugar and vanilla until light and creamy. Add eggs, 1 at a time, beating well after each addition. Gently fold n flours and remaining lemon butter. Spoon into tins over blueberries.
3. Bake for 20-25 mins or until cakes are cooked through when tested with a skewer. Stand cakes for 5 mins then turn out to cool. Serve with custard or cream.