Created by lazyme on January 24, 2015
Step 1: Preheat oven to 350.
Step 2: Coat a large skillet with cooking spray; add oil, and place over medium heat until hot. Add onion, and saute 5 minutes.
Step 3: Add beer; cook 12 minutes or until liquid evaporates, stirring occasionally.
Step 4: Remove onion mixture from heat, and set aside.
Step 5: Cook potato slices in boiling water for 8 minutes or until crisp-tender; drain.
Step 6: Rinse under cold water, and drain well.
Step 7: Place 1/3 of potato slices in an 11x7-inch baking dish coated with cooking spray, and sprinkle with half of salt and half of pepper.
Step 8: Spread half of onion mixture over potato slices.
Step 9: Repeat procedure with the remaining potato slices, salt, pepper, and onion mixture, ending with potato slices.
Step 10: Place flour in a bowl. Gradually add milk, stirring with a wire whisk until blended. Pour milk mixture evenly over potato slices.
Step 11: Cover with aluminum foil, and cut 3 (1-inch) slits in foil.
Step 12: Bake at 350 for 45 minutes.
Step 13: Uncover; sprinkle with cheese, and bake an additional 10 minutes or until cheese melts.