Homemade Alfredo Sauce

In a large saucepan, heat butter over medium heat. Add shallots; cook and stir until tender, 2-3 minutes. Add garlic; cook 1 minute longer. Add cream; cook and stir until heated through. Stir in Asiago, 1/2 cup Parmesan, Romano cheese, salt and pepper; bring to a boil, stirring constantly. Reduce heat; simmer, uncovered, until thickened, about 10 minutes, whisking occasionally., Meanwhile, cook pasta according to package directions. Drain, reserving 1 cup pasta water; place pasta in a large bowl. Add sauce; toss to coat. Thin as desired with reserved pasta water. Serve with the remaining 1/2 cup Parmesan cheese.