Preheat oven to 400°F Place the tart pan on shallow baking sheet; fit the tart pan with aluminum foil or parchment paper, fill with beans or pie weights, and bake in the middle of preheated oven for 15 minutes; carefully remove the foil with beans and bake for another 5 minutes.
03For filling: Turn the heat down to 375F; quarter, core, and peel the apples; cut into 1/4" lengthwise slices; toss them in a bowl with the sugar and cinnamon, then arrange them in the crust in concentric circles; bake in the upper third of preheated oven for about 20 minutes, or until they start to color and are almost tender; remove from oven and let cool while preparing the custard.
04For custard: Beat the egg and sugar together in a mixing bowl until mixture is thick, pale yellow, and falls back on itself forming a slowly dissolving ribbon; beat in the flour, then the cream, and finally the cognac; pour the mixture over the apples; it should come almost to the top of the pastry shell; return to oven for 10 minutes, or until cream begins to puff.
05Sprinkle with icing sugar (placed in a sieve and sprinkled evenly over) and return to oven for 15 to 20 minutes more.
06Tart is done when top has browned and a knife plunged into the custard comes out clean; unmold the tart; cool 10 minutes and serve.