In a large bowl, mix cream cheese, sour cream, mustard, garlic powder till smooth. Slowly whisk in the beer until smooth. Stir in the grated cheese and chopped bacon.
Spoon the dip into the slow cooker and turn the heat to low. Cook for about 3-4 hours and stir often to make sure the sides do not burn.
In the 30 minutes of cooking, stir in the heavy cream 1 tablespoon at a time.
Once all the cheese is melted and dip is smooth turn the heat to warm. Top with remaining bacon and onions. Serve with pretzel bites.