Heat the oven to 180C/160C fan/gas 4. Lightly butter a 12 hole muffin tin. Unroll the sheet of pastry and use a 10cm circular pastry cutter to cut 12 circles out of the pastry sheet. Press the cut circles into the holes of the tin, making sure they come right up and slightly over the top – pushing out any creases. Chill the pastry in the fridge for 20mins. Scrunch up 10cm x 10cm squares of baking paper and then un-scrunch and use to line each of the pastry tarts, then fill with baking beans, rice or dried pulses. Bake for 10 mins, then remove the paper and beans and bake for 10 mins longer, until golden brown. Set aside to cool a little.
Make the filling by beating together the butter and sugar until light and fluffy, then whisk in the egg, followed by the flour (the flour will prevent the mixture from splitting). Fold in the ground almonds. Spoon a level tsp of cherry jam into each of the pastry shells, followed by a tablespoon of the frangipane mixture. Bake for 20 mins, until the frangipane is golden and springy. Set aside to cool completely. Neaten the edges of the pastry with a small knife or scissors if you like.
Mix the icing sugar with 2 tbsp water. Spread the icing over each of the tarts, top each with a glacé cherry, leave to set for 20 mins, then serve with tea.