Cook pasta according to package directions. Meanwhile, in a large saucepan, saute garlic in butter for 1 minute. Stir in flour and pepper until smooth; gradually add milk. Bring to a boil; cook and stir for 1-2 minutes or until thickened. Reduce heat; stir in 2 cups of cheese until melted. Remove from the heat.
Drain pasta; add pasta and 1/3 cup bacon to cheese sauce. Transfer to a greased 2-qt. baking dish. Cover and bake at 350° for 30 minutes. Uncover; sprinkle with remaining cheese and bacon.
Bake 5-10 minutes longer or until cheese is melted.