Grease a tart mould with a lifting base (26 cm Ø) and dust with flour. For the dough, put 300 g flour, sugar, 2 tablespoons cold water and 200 g margarine in pieces in a bowl. Knead first with the dough hooks of the mixer, then quickly with your hands to a smooth dough.
Press the mould to a base with your hands, forming a rim. Chill for at least 30 minutes.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Wash the nectarines and cut them into slices from the stone. Sort blueberries, wash and drain well. Stir jelly until smooth.
Mix slightly with fruit and starch.
Sprinkle the dough base with nuts. Spread fruit on top. Bake in a hot oven for about 40 minutes. Remove the tart and let it cool down.