Mix together the butter, sugar, flour, a pinch of salt and the egg in a food processor to make a dough, then wrap and leave to rest in the fridge for 30 mins. The dough should be cold but still easy to work with by the time you roll it out.
Meanwhile, make the frangipane filling. Melt the butter in a pan over a low heat, then set aside to cool slightly. Beat the sugar with the eggs and lemon zest in a bowl until creamy. Pour in the melted butter while continuing to beat, then add the ground almonds (or almond flour) and fold into the mixture. Heat oven to 175C/155C fan/gas 3½.
Line a buttered tart tin or ring mould (approximately 23cm) with the rolled-out pastry dough, then trim any overhanging edges. Spread the frangipane evenly into the tin and arrange the cherries on top with some of their syrup, so the top of the tart is covered in a thin layer.
Put the tart in the oven and bake for about 40-45 mins until golden brown, puffed and firm to the touch. Leave to cool on a rack. Dust with some icing sugar, if you like, before serving in slices.