Start this recipe by making the pastry. Place the flour, baking powder, icing sugar and butter together in a bowl and rub together with your fingertips until the mixture resembles breadcrumbs. Add the lemon zest and egg yolk and mix to a soft pastry. Chill the pastry for 15 minutes before using it to line a 25cm fluted flan tin. Spoon 2 tablespoons of the apricot jam over the pastry case and spread out evenly. Put the pastry case aside while you make the frangipan filling. Place the butter and sugar in a bowl and cream together till light. Stir in the eggs, along with the lemon zest, ground almonds and plain flour. Carefully spoon the frangipan over the apricot jam in the pastry case and spread out using a palette knife. Bake in the oven at 180`c for about 45 minutes, or until the frangipan is golden brown and cooked through. Remove the baked tart from the oven and leave to cool completely. When the tart has cooled, slice and carefully arrange the peaches on top of the frangipan. Make the jelly, according to the packet instructions and allow to cool slightly to thicken. Carefully glaze the peaches with the apricot jelly and allow to set completely before serving.