Grease a tart mould (26 cm Ø; no lifting base). Melt icing sugar in a pot at low to medium heat. Add 2 tablespoons butter, maple syrup and 1 tablespoon cinnamon. Let it caramelize while stirring occasionally. Fill the caramel into the tart and spread evenly.
Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Peel the pears, cut them in half, remove the seeds and place them in the mould on the caramel with the cut surface facing down. Coarsely chop the walnuts and sprinkle them on the pears.
Roll out the dough, 1⁄3 Cut the dough from the short side and use it for other purposes. Remove baking paper from the rest of the dough and place the dough over the tart tin, pulling the short side slightly apart. Cut off the protruding edge. Press the dough lightly against the pears. Bake in a hot oven for about 25 minutes. Turn the tart out of the tin. Tastes hot or cold.