In a dutch oven or heavy bottomed pot, melt the butter over medium heat. Add the salt, sugar, and garlic powder, stirring to combine, followed by the onions, bratwursts, and beer. Bring the mixture to a boil. Reduce heat and simmer until bratwursts are firm to the touch, about 10-12 mins.

Transfer the bratwursts to a plate and continue to cook the onions in the beer until the liquid has completely cooked out, and the onions are turning golden, about 30-40 minutes. Add the bratwursts back to the pot and brown all over.

Serve the bratwursts topped with the onions. Yum!