Preheat oven to 400.
Cook and drain macaroni as directed on package.
In large skillet, melt butter over medium heat. Using a whisk, add flour, salt, pepper, and garlic. Cook 2-3 minutes, or until mixture is golden color, stirring constantly.
Beat in milk. Continue stirring until mixture begins to boil.
Remove from heat. Stir in 2 cups cheese and basil.
Pour into lightly greased 2-quart casserole dish.
Sprinkle remaining cheese evenly over the top.
Bake for 20 minutes, or until lightly browned.