Stuffing-Stuffed Onions

Remove and fill the sauteed onion with the coarsely chopped filling to spice up the hearty casserole option.
Preheat the oven to 425 degrees. Cut a thin slice from the bottom (rounded end) of each onion, forming the base for the onion stand. Cut 1/2 inch from the end of the sprout of each bulb and discard. Peel the onion. Remove and leave the middle of each onion, leaving 2 layers of onion in the form of a thick shell. Finely chop 1 cup chopped onion. If desired, leave the remaining onion centers for another use.Place the chopped onion in a 2-quart baking dish and pour in 1 cup of broth. Cut 2 tablespoons of butter into 8 parts and place 1 part on each onion. Cover with aluminum foil and bake at 425 ° C for 25-30 minutes or until the shells are soft. Transfer from the oven to a wire rack and let cool for 20 minutes.Pour the onion liquid into a measuring cup and add the stock (about 1/4 cup) to make 1 cup. Reduce the oven temperature to 350 degrees.Melt 4 tablespoons butter in a large skillet over medium-high heat; add the celery and 1 cup chopped onion and simmer for 5 minutes or until soft. Add the parsley and sage and cook, stirring constantly, for 1 minute or until fragrant. Add the breadcrumbs, salt, pepper, and 1 cup of the remaining stock mixture. Remove from heat.Fill the onion slices with the filling and place in a shallow 9-inch baking dish or pie dish. Add the remaining 1/4 cup broth to the pan. Bake at 350 ° C for 30-35 minutes or until the minced meat is golden brown and thoroughly warmed through. Transfer to a serving platter. Stir the remaining 2 tablespoons of butter into the cooking liquid and spoon over the onion.