- 4 pounds boneless magret duck breast halves with skin (about 4)
- 1/2 cup finely chopped shallots
- 2 garlic cloves, chopped
- 2 tablespoons sugar
- 1/3 cup raspberry vinegar
- 1 cup demi-glace (6 1/2 ounces; preferably D'Artagnan duck and veal demi-glace)
- 2 cups raspberries(12 ounces), divided
- 1 1/2 tablespoons unsalted butter, cut into bits
- Put a large shallow flameproof roasting pan in middle of oven and preheat to 400°F.
- Pat duck dry and trim off any excess fat. Score skin in a crosshatch pattern at 1/2-inch intervals with a sharp knife, then season with 1 tsp salt and 1/2 teaspoon pepper (total). Roast, skin side down, in hot pan until an instant-read thermometer inserted diagonally into center registers 125°F, 20 to 25 minutes.
- Turn on broiler. Turn duck skin side up. Broil 4 to 6 inches from heat until golden brown, about 2 minutes. Transfer duck to a cutting board and let rest (skin side up) 10 minutes.
- While duck rests, pour off all but 1 tablespoon fat from pan, then add shallots and garlic and saué over medium-high heat until golden brown, about 2 minutes. Add sugar and cook, stirring, until dissolved. Stir in vinegar, scraping up brown bits. Add demi-glace and bring to a simmer. Stir in half of raspberries.
- Force sauce through a fine-mesh sieve into a small saucepan, discarding solids. Skim off excess fat. Over low heat, swirl in butter. Remove from heat and add remaining raspberries.
- Slice duck and serve with sauce.