Green Bean Casserole with Bacon

Name: Green Bean Casserole with Bacon
Ingredients: Safflower oil, for frying; 1 shallot, peeled and thinly sliced in rings; ¼ cup unbleached all-purpose flour; Kosher salt and freshly ground pepper; 1 ½ pounds green beans; 12 slices bacon (¾ pound), cut crosswise in ¼-inch pieces; 2 tablespoons unsalted butter; 1 medium onion, cut into ¼-inch dice (1 ⅓ cups); 8 ounces cremini mushrooms, thinly sliced; 3 cups milk, room temperature; 1 teaspoon Dijon mustard; ⅛ teaspoon cayenne pepper; 1 teaspoon Worcestershire sauce