In a large skillet, melt the butter and olive oil over medium heat.
2 tablespoons butter, 2 tablespoons olive oil
Add the onions and sugar, and cook slowly for about 20 to 25 minutes, stirring often, until they’re caramelized - they should be soft and golden brown in color.
3 large sweet onions, 1 teaspoon granulated sugar
Stir in the garlic, cooking for about a minute. Pour in the wine to deglaze the pan, scraping up all that flavorful goodness.
2 cloves garlic, ½ cup dry white wine
Add the beef broth, thyme, and a teaspoon each of salt and pepper. Let it simmer for about 5 minutes.
1 tablespoon fresh thyme, 1 cup beef broth, black pepper, kosher salt
Meanwhile, cook your pasta according to the package directions. Drain it and save about ½ cup of the pasta water.
8 oz pasta
Stir the cream and cheese into the onions until the sauce is smooth and creamy.
½ cup heavy cream, 1 cup Gruyère cheese
Add the pasta and toss to coat, adding a little pasta water if the sauce feels too thick.
Taste and add additional salt and pepper to taste as desired, and serve hot.