French Onion–Stuffed Onions

• temps total: 1 hour 15 minutes

Ingrédients

4 (about 12-ounce) white onions

1 cup beef stock

2 tablespoon olive oil, divided

1/4 teaspoon kosher salt, plus more to taste

1/4 teaspoon black pepper, plus more for garnish

1 cup Frenched Onions, warmed

3/4 teaspoon chopped fresh thyme, plus additional leaves for garnish

1 1/4 cups Gruyère cheese, shredded (about 5 ounces), divided

4 (3/4-inch-thick) slices rustic sourdough bread

Instructions

Preheat oven to 450°F. Trim about 1/4 inch from the root end and about 1 inch from the stem end of each onion. Peel onions, and remove outermost onion layer. Scoop out flesh from center of each onion using a small spoon to create a cavity about 1 inch deep, leaving about 2 onion layers intact around the sides. The base should be slightly thicker. Reserve onion flesh. Discard peels, trimmings, and the outer onion layer.

Finely chop onion flesh. Spread 1 1/2 cups chopped onion in a 9-inch square baking pan, and pour in beef stock. (Discard any remaining flesh, or reserve for another use.) Nestle hollowed onions, open end up, in pan; drizzle with 1 tablespoon oil, and sprinkle evenly with salt and pepper.

Cover pan tightly with aluminum foil. Bake in preheated oven until hollowed onions are softened, about 20 minutes. Uncover, and continue baking until liquid in pan has almost completely evaporated and hollowed onions are tender, 20 to 25 minutes. Remove pan from oven. (Do not turn oven off.)

Transfer hollowed onions to a paper towel–lined plate. Stir Frenched onions and thyme into onion mixture in pan. Season to taste with additional salt. Stuff each hollowed onion with 1 tablespoon Gruyère and about 1/3 cup Frenched onion mixture.

Place bread slices on a rimmed baking sheet; drizzle evenly with remaining 1 tablespoon oil. Top each slice with 1 stuffed onion. Sprinkle onions evenly with remaining 1 cup Gruyère, letting some spill onto bread. Bake at 450°F until Gruyère is melted and beginning to brown, 5 to 8 minutes. Garnish with thyme leaves and additional black pepper. Serve hot.