Preheat the oven to 400°
Combine the flour, sugar, baking powder, and salt.
In a separate bowl, combine egg, milk, and melted butter.
Gently stir the milk mixture into the flour mixture. Mix carefully, trying not to overmix, but not leaving dry bits either.
Grease a muffin tin, or use muffin papers. Put 1 scoop of batter into each muffin cup. Add 1 tsp jam on top of the batter in each muffin cup. Then put remaining batter into each cup to cover the jam. Sprinkle with sugar, if desired.
Bake for 20-25 minutes.