Roasted Stuffed Onions

Ingredients

• 14 cups baby spinach trimmed coarsely chopped
• 1 lb bacon sliced
• 1 teaspoon pepper black
• 3 slices celery stalks 
• 3  garlic clove minced
• 1 teaspoon salt 
• 10 oz roasted cashews salted coarsely chopped
• 1.3 cups turkey stock 
• 0.5 cup butter unsalted melted
• 4 lb onion red yellow

Equipment

• bowl
• frying pan
• paper towels
• oven
• baking pan
• aluminum foil
• ice cream scoop
• slotted spoon

Directions

1. Cut a 1/2-inch-thick slice from tops of onions, discarding tops, and trim just enough from bottoms for onions to stand upright. Scoop out all but outer 2 or 3 layers from each using a small ice cream scoop or spoon (don't worry if you make a hole in the bottom), reserving scooped-out onion and onion shells separately.
2. Coarsely chop enough scooped-out onion to measure 3 cups.
3. Cook bacon in 2 batches in a 12-inch heavy skillet over moderate heat, stirring, until crisp, about 10 minutes, then transfer with a slotted spoon to paper towels to drain, reserving about 1/3 cup fat in skillet.
4. Add chopped onion, celery, salt, and pepper to skillet and sauté over moderately high heat, stirring, until vegetables are softened, about 5 minutes.
5. Add garlic and sauté, stirring, 1 minute.
6. Transfer mixture to a large bowl and stir in spinach, bread, cashews, butter, 1 cup stock, and bacon, then cool completely.
7. Preheat oven to 425°F.
8. Arrange onion shells, open sides up, in a 13- by 9- by 2-inch baking pan, then add 1/2cup water and cover pan tightly with foil. Roast onions in middle of oven until tender but not falling apart, 25 to 30 minutes.
9. Reduce oven temperature to 350°F.
10. Transfer shells to a work surface and pour off water in pan. Fill shells with stuffing, mounding it, and return to pan. Reserve 5 to 7 cups stuffing for turkey cavity, then put remaining stuffing in a buttered shallow 3 1/2-quart baking dish and drizzle with remaining 1/4 cup stock.
11. Bake stuffed onions and stuffing in dish in middle of oven, uncovered, until heated through, about 25 minutes.
12. Stuffing can be prepared and onions can be stuffed 1 day ahead and chilled, covered. Bring stuffed onions to room temperature before baking.