1. Preheat oven to 180ºC. Break eggs into a bowl and whisk adding sugar till light and frothy. Add vanilla essence and mix.
2. Sift refined flour, salt and baking powder into another bowl. Melt butter. Add the egg mixture to the flour mixture and mix gently. Add melted butter and mix. Add milk and mix. Add lemon rind and mix. Add blueberry jam and mix lightly.
3. Pour the batter into the muffin moulds and bake in the preheated oven for ten to fifteen minutes or till they rise properly.
4. Remove them from the moulds when slightly cool and serve warm.