Make the caramelized onions. Thinly slice one whole red or white onion lengthwise. Heat two tablespoons butter in a large pan or skillet over medium heat until melted and bubbling. Gradually add onions, and cook stirring occasionally, until onions are soft. Repeat until all onion slices have been added. Reduce heat to medium low or low and cook, stirring occasionally, for about 15-20 minutes until onions are super soft and caramelized. They should turn a light to medium brown color. Set aside.

Make the beer cheese sauce. In a small to medium saucepan or pot, melt butter over medium heat. Add flour and whisk or stir frequently for about 3 minutes, until flour and butter have formed thick paste. Add spices and stir to combine. Add beer. Stir until flour mixture is smoothly blended into beer. Add half and half. Continue to whisk until smooth. Reduce heat to low and gradually add shredded cheese, about one cup at a time. Stir until cheese is melted and blended into the sauce, and keep adding cheese until you reach desired thickness. Keep sauce warm, on very low heat while you cook the brats. Give the sauce a good stir before serving.

Boil the brats. Place brats in deep pot or dutch oven on the stove. Pour beer into pot covering brats. Add sliced onion to the pot. Bring brats to a boil, then reduce heat and simmer until brats are cooked, about 15 to 20 minutes.

Grill brats. While brats are boiling, preheat grill to medium heat. Once boiled, using tongs, transfer the brats directly to the grill grates and sear on all sides, about 2-3 minutes a side until golden brown or charred to your preference.

Serve brats on a toasted bun with the condiments of your choice.