Ingredients

• 2 medium white onions, unpeeled
• 4 cipolline onions, unpeeled
• 4 small shallots, unpeeled
• 1/2 cup (1 stick) unsalted butter
• 3 tablespoons apple cider vinegar
• Kosher salt
• Ingredient info: Cipolline onions, small flat onions, are available at Italian markets, specialty foods stores, and some supermarkets.

Instructions

1. Preheat oven to 400°F. Cut white onions, larger cipolline onions, and shallots almost in half, leaving root ends intact. Pry each open slightly to expose cut sides. Place white onions root side down in a foil-lined roasting pan and roast until just beginning to soften and brown, 75-90 minutes.
2. Add cipolline onions and shallots to roasting pan root end down and roast until all onions and shallots are soft and deeply colored, about 1 hour longer.
3. Just before onions finish cooking, melt butter in a small saucepan and cook, swirling occasionally, until butter is brown and smells nutty, 5-8 minutes. Let cool slightly; whisk in vinegar and season brown butter with salt.
4. Divide onions and shallots among plates, leaving skins on; spoon brown butter over.