Cook pasta according to package directions, omitting salt and fat.
Drain in a colander over a bowl, reserving 1/4 cup cooking liquid.
While pasta cooks, cook bacon in a large nonstick skillet over medium-high heat 4 minutes or until crisp, stirring occasionally.
Remove bacon from pan, reserving drippings.
Add garlic to drippings in pan; saut 1 minute, stirring constantly.
Sprinkle flour over garlic; cook 30 seconds, stirring constantly. Gradually add milk, stirring constantly; cook 2 minutes or until bubbly and slightly thick, stirring constantly. Reduce heat to low. Gradually add cheese, stirring until cheese melts. Stir in salt and reserved 1/4 cup cooking liquid.