Meanwhile, in 8-inch skillet, heat oil over medium heat. Add onion and cook 4 minutes, stirring occasionally. Add bratwurst; cook 4 to 5 minutes or until heated through. Carefully stir in cream cheese, Cheddar cheese and beer; pan will be full. Cook 2 to 3 minutes, stirring constantly, until cheeses are completely melted. Remove from heat; top with green onions, and serve with pretzel bites.