Stuffed Cornish Game Hens With Leek Stew

Name: Stuffed Cornish Game Hens With Leek Stew
Ingredients: 7 tablespoons unsalted butter; 2 ounces bacon, cut crosswise into 1/2-inch pieces; 1/2 small onion, finely chopped; 1/2 Granny Smith apple, peeled, cored, and chopped into 1/4-inch pieces; 3 ounces baguette, cut into 1/2-inch cubes and toasted; 1/2 teaspoon freshly grated orange zest; 1 1/2 teaspoons finely chopped fresh sage; 1/2 teaspoon ground cinnamon; 1 cup store-bought low-sodium chicken stock, warmed; 1 large egg, lightly beaten; 4 Cornish game hens (1 pound each); 3 tablespoons olive oil; Coarse salt and freshly ground black pepper; Maple Vanilla Gastrique, for serving (optional); Leek Stew, for serving (optional)