For the muffins
Heat the oven to 200°C (180° fan) gas 6.
Place paper cases in an 8 hole muffin tin.
Put the butter, sugar, ground almonds, polenta, baking powder, vanilla, egg, egg yolk and salt into a mixing bowl and whisk with an electric whisk until smooth and blended.
Whisk in the orange zest and 1 tablespoon juice.
Spoon into the paper cases and bake for 12-15 minutes until golden and firm.
For the topping
Sift the icing sugar into a bowl and stir in about 1 tablespoon orange juice to make a syrup.
Spoon over the warm cakes and decorate with marzipan hearts.