For the cupcakes: heat the oven to 200°C (180° fan) 400°F gas 6. Place paper cases in a 12 hole bun tin.
Mash the bananas. Beat the eggs with the vanilla, butter and sugar in a mixing bowl until light and fluffy. Beat in the banana.
Sift in the flour and baking powder and lightly mix, until just combined.
Spoon into the paper cases and bake for about 25 minutes until golden and risen. Cool in the tin for 5 minutes, then place on a wire rack to cool completely.
Spoon a little dulce de leche in the centre of each cake and place a chocolate heart on top.