Gather the ingredients.
Cook pasta according to package directions.
Meanwhile, heat 2 tablespoons of butter and the olive oil in a sauté pan over medium heat. When the butter is melted, add the onion and salt. Sauté until onions are softened and golden brown, about 20 minutes.
Add the garlic and flour. Stir to incorporate the flour into the fat. Cook for 2 to 3 minutes on low heat to cook off the flour flavor.
Add the beef broth, Worcestershire sauce , and the leaves from the thyme sprigs, stirring with a spoon while incorporating. Cook for 2 to 3 minutes or until the sauce is thickened.
Add the remaining tablespoon of butter to a small sauté pan. Heat until melted and then add the breadcrumbs, toss to coat and toast on low heat until lightly browned.
Add the cooked pasta and the Gruyère cheese into the pan. Toss to combine. The heat from the sauce will melt the cheese just enough.
Top with toasted breadcrumbs and additional shredded Gruyère if you wish. Serve immediately.
