- 2 tablespoons butter
- 4 medium-size Vidalia onions, thinly sliced (about 6 1/2 cups)
- 1 1/2 teaspoons chopped fresh thyme
- 3/4 teaspoon salt
- 1/2 teaspoon pepper
- 1/2 (15-oz.) package refrigerated piecrusts
- Parchment paper
- 1 egg white, lightly beaten
- 3/4 cup (3 oz.) shredded Gruyère cheese
How to Make It
Preheat oven to 425°. Melt butter in a large nonstick skillet over medium-high heat; add onion and next 3 ingredients. Cook, stirring occasionally, 8 minutes or until tender.
Unroll piecrust onto a lightly floured surface. Pat or roll into a 12-inch circle. Place piecrust on a parchment paper-lined baking sheet. Brush with egg white. Sprinkle 1/2 cup cheese in center of crust. Spoon onion mixture over cheese, leaving a 2 1/2-inch border. Sprinkle remaining 1/4 cup cheese over onion. Fold piecrust border up and over onion, pleating as you go and leaving a 4-inch-wide opening in center. Brush crust with egg white.
Bake at 425° on bottom oven rack 17 to 19 minutes or until crust is golden. Let stand 5 minutes before serving.