For crpes
2/3 cup whole milk
1/4 cup plus 1 tablespoon all-purpose flour
1 large egg
11/2 tablespoons unsalted butter, melted, plus additional for brushing skillet
1 teaspoon sugar
1/4 teaspoon salt

For quince pure
3 cups water
2/3 cup sugar
4 (3-inch-long) strips of fresh lemon zest (1/2 inch wide)
1 1/2 lb quince (2 medium), peeled and halved, then each half cut into 6 wedges and cored
1/2 teaspoon vanilla
2 tablespoons Calvados
2 teaspoons fresh lemon juice

For souffls
2 large egg whites
1 1/2 tablespoons granulated sugar
1 1/2 tablespoons unsalted butter, melted
Confectioners sugar for dusting

Make crpe batter:
Whisk together all crpe ingredients until smooth, then chill, covered, 30 minutes.

Poach quince:
Combine water, sugar, zest, and a pinch of salt in a 3-quart heavy saucepan and cook over moderate heat, stirring, until sugar is dissolved. Add quince and simmer, covered, until fruit is very tender but not falling apart, 1 to 1 1/4 hours. Discard zest.

Cook crpes while fruit poaches:
Lightly brush an 8- to 9-inch nonstick skillet with butter, then heat over moderately high heat until hot but not smoking. Holding skillet off heat, pour in a scant 1/4 cup batter, immediately tilting and rotating skillet to coat bottom. (If batter sets before skillet is coated, reduce heat slightly.) Return skillet to heat and cook crpe until just set and golden around edges, 10 to 15 seconds. Loosen edge of crpe with a heatproof rubber spatula, then transfer crpe to a plate. Brush skillet with more butter and make 3 more crpes in same manner, stacking crpes on plate.

Finish preparing quince:
Measure out 3/4 cup poached fruit with a slotted spoon and 3 tablespoons cooking syrup (reserve remainder in saucepan), then pure in a food processor with vanilla and 1 tablespoon Calvados until smooth.

Transfer remaining fruit from reserved syrup with a slotted spoon to a bowl. Pour syrup through a fine-mesh sieve into another bowl, then return to saucepan and boil until reduced to about 1/2 cup, 8 to 12 minutes. Stir in lemon juice and remaining tablespoon Calvados and cool.

Measure out 3/4 cup reserved fruit, then chop and set aside. Stir remaining fruit into reduced syrup and set aside separately.

Make souffls:
Put oven rack in middle position and preheat oven to 400F.

Beat whites with a pinch of salt using an electric mixer at medium-high speed until they just hold soft peaks. Add granulated sugar in a slow stream, beating, and beat at medium-high speed until whites just hold stiff peaks. Fold one third of whites into quince pure, then fold in remaining whites gently but thoroughly. Gently fold in chopped fruit.

Brush bottom sides of crpes with some melted butter and put in a 15- by 10-inch shallow baking pan (about half of each crpe will hang over). Divide souffl mixture among crpes, spooning it in center and spreading it over half of each crpe. Gently fold other half of each crpe over filling to rest on top. Bake until filling is puffed, set, and pale golden in spots, 10 to 12 minutes.

Dust crpes with confectioners sugar and serve immediately with reserved quince and syrup.

Cooks' notes:
Crpes can be made 1 day ahead and cooled completely, uncovered, then chilled, covered.
Poached quince in syrup and quince pure will improve in color if made at least 1 day ahead and can be made 5 days ahead. Cool poached quince in syrup completely, uncovered, then chill, covered. If possible, make quince pure at least 1 day after poaching (to allow color of quince to improve) and chill, covered.