– 2 pounds chicken breasts, cut into 1-inch cube – 2 Tablespoons vegetable oil, divided – 1 medium yellow onion, thinly sliced – 2 cloves garlic, minced – 1/4 cup dry sherry or white wine – 1 1/2 Tablespoons all-purpose flour – 1 teaspoons beef bouillon paste – 2 teaspoons Worcestershire sauce – 1/4 cup heavy cream – 2 teaspoons fresh thyme leaves, plus more for garnishing FOR THE TOPPING: – 1 French baguette, cut into 1/2-inch slice – 2 cups shredded Gruyère cheese