Instructions: Butter a 10-inch tart pan with removable bottom; set aside.

Prepare the crust: In a medium bowl, combine flour and 1/2 teaspoon salt. Add 8 tablespoons (1 stick) chilled butter, and combine with fingers or a pastry blender until it has the texture of coarse meal. Add 1/2 cup ice water, and stir just until a dough forms. Form into a disk, and wrap in plastic wrap. Chill for at least 15 minutes.

Heat oven to 375 degrees. On a lightly floured surface, roll out dough to 1/8-inch-thick round. Fit dough into prepared tart pan; trim excess. Line with a parchment paper round, and fill with pie weights. (If you dont have pie weights for blind baking the crust, you can use dried beans, rice, or clean, round pebbles.) Chill for 15 minutes. Transfer to oven, and bake for 15 minutes. Remove pie weights and parchment paper. Bake for 5 minutes more. Remove from oven, and set aside.

In a large skillet, heat remaining 4 tablespoons butter. Add onions, and cook, stirring frequently, until slightly browned and softened, about 15 minutes. Remove from heat.

In a small bowl, combine beaten egg, cream, remaining 1 teaspoon salt, pepper, and nutmeg. Stir in onions.

Sprinkle baked tart shell with cheese. Spread onion mixture evenly over cheese. Bake until set, 35 to 40 minutes. Serve immediately.

This recipe yields 6 servings.

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