4 Tablespoons unsalted butter 1 cup chopped onion 1 garlic clove, minced 1/4 cup gf flour 3-1/2 cups milk 2-1/2 cups sharp white cheddar, grated 1 cup Parmesan cheese, grated 8 ounces mascarpone cheese 1/2 cup Italian parsley, chopped 1 lb. elbow gf pasta
Directions
Preheat oven to 350 degrees F. Butter a 13x9x2 inch glass baking dish. Melt 1 Tablespoon butter in a large skillet over medium heat. Add onion and saute until tender. Add garlic and cook for 1 minute. Add remaining butter and when melted, add flour; cooking and stirring for 1 minute. Gradually stir in milk. Simmer for about 5 minutes or until liquid thickens enough to coat the back of a spoon. Remove from heat and add all cheeses; stirring until sauce is smooth. Add parsley and season to taste with salt and pepper. Cook pasta in boiling salted water until tender but firm. Drain and return to the pot. Add sauce to the pot of pasta and mix to blend. Pour mixture into the prepared baking dish. Bake for 30 minutes. Turn oven to broil and place dish under broiler for 1-2 minutes to brown top slightly. Remove from oven; let cool for 5 minutes, then serve.