This savory caramelized onion tart can be served warm or at room temperature.

Savory Caramelized Onion Tart

Pastry:
1 2/3 cups all-purpose flour
1/4 teaspoon salt
1/2 cup butter, softened
1 egg yolk
2 to 3 tablespoons milk

Filling:
1/4 cup butter
3 medium onions, thinly sliced
3 large eggs
1 cup sour cream
1/2 teaspoon salt
1/4 teaspoon hot pepper sauce
1 cup (4 ounces) shredded Wisconsin Gruyère cheese - divided use

For Pastry: Combine flour and salt in food processor. Cut butter into six pieces; add to flour mixture. Process using on/off pulsing until mixture resembles corn meal. Add egg yolk and 2 tablespoons milk; process until dough leaves side of bowl. Add additional milk by teaspoons, if necessary, until dough holds together when pressed. Shape dough into a disc; wrap in plastic wrap. Refrigerate 30 minutes or until firm.
For Flling: Melt butter in a large skillet over medium-high heat. Add onions; cook 5 minutes, stirring occasionally. Reduce heat to medium; continue cooking about 15 minutes or until onions are softened and caramelized (browned); remove from heat.
In a large bowl, beat eggs. Add sour cream, salt and pepper sauce; mix well. Add onion mixture; mix well. Stir in 1/2 cup of the cheese.
Roll dough out on lightly floured surface to 1/4 inch thickness with rolling pin. Cut 12-inch circle; transfer to a10-inch tart pan with removable bottom or 10-inch pie plate. Press lightly onto bottom and sides of pan; trim edges even with edge of pan. Spread onion mixture evenly over crust. Sprinkle with remaining 1/2 cup cheese.
If desired, cut scraps of pastry with decorative cookie cutters; place over tart.
Bake at 450°F (230°C) for 10 minutes.
Reduce oven temperature to 350°F (175°C); continue baking for 30 to 35 minutes, or until golden brown and set in center.
Let stand at least 20 minutes before serving.
Remove rim of tart pan; transfer to platter. Cut into 12 wedges; serve warm or at room temperature.

Makes 12 servings.

Recipe provided courtesy of Wisconsin Milk Marketing Board, Inc.