Caramelized Onion and Tomato Pie

In a 10-inch cast-iron skillet, cook bacon over medium heat until crisp. Remove from skillet, and let drain on paper towels. Reserve 1 tablespoon drippings in skillet and heat over medium-high heat. Add onion and bell pepper; cook until lightly browned around the edges, about 6 minutes. Reduce heat to medium-low. Cover and cook until golden brown and tender, about 35 minutes more, stirring occasionally. Spoon onion mixture into a bowl. Let onion mixture and skillet cool completely.

Line 2 baking sheets with paper towels. Arrange tomato slices in a single layer on prepared pans; sprinkle with 1 teaspoon salt. Let stand 30 minutes. Pat tomatoes with paper towels.

Preheat oven to 425°.

On a lightly floured surface, unroll 1 piecrust. Lightly brush with 2 teaspoons water. Top with remaining piecrust. Roll piecrust into a 14-inch circle. Transfer to skillet, pressing into bottom and up sides. Trim excess dough to ½-inch from edge of skillet. Fold edges under; crimp as desired.

In a small bowl, stir together cooled onion mixture, cheeses, mayonnaise, thyme, pepper, egg, and remaining ½ teaspoon salt. Spread one-third of mayonnaise mixture in bottom of prepared crust. Sprinkle with 2 teaspoons breadcrumbs. Arrange half of tomatoes, overlapping slightly. Repeat layers once. Top with remaining mayonnaise mixture.

Bake 15 minutes.

Reduce oven temperature to 375°. Loosely cover filling with foil; bake until golden brown, about 30 minutes more. Let cool on a wire rack. Sprinkle with bacon. Garnish with thyme and pepper, if desired.