Spoon 6 heaped teaspoons of jam onto a lined tray and freeze.
Preheat the oven to 180°C fan.
Melt the baking spread and mix with the caster sugar.
Whisk in the eggs, vanilla and milk.
Fold in the self-raising flour and baking powder until just combined.
Spoon batter into each case until around halfway full.
Place a frozen jam portion into the centre of each, keeping it away from the bottom and sides.
Cover completely with the remaining muffin batter.
Add a little swirl of jam to the top of each muffin.
Bake for 18–22 minutes, until risen and golden.
While still slightly warm, brush the tops with melted jam and dip/roll in caster sugar.
Leave to cool slightly before breaking one open to reveal that jammy centre
