Bratwurst with Mushroom Gravy

INGREDIENTS:

6 tablespoons unsalted butter , divided
1 yellow onion , chopped
1 clove garlic , minced
16 ounces fresh cremini or button mushrooms , brushed clean and sliced
2 cups strong beef broth (e.g., use extra beef broth base or granules)
1/2 teaspoon salt
1/4 teaspoon freshly ground black pepper
1 tablespoon cornstarch dissolved in 2 tablespoons water
chopped fresh parsley for serving
4 German bratwursts

DIRECTIONS:

Melt 2 tablespoons of the butter in a skillet over medium-high heat and fry the onions until beginning to brown, 6-8 minutes. Add the garlic and cook another minute. Add the mushrooms and cook 7-8 minutes or until the liquid has evaporated and the mushrooms are beginning to brown a little. Add the beef broth, salt and pepper and bring to a boil. Reduce the heat, cover and simmer for 5-10 minutes. Stir in the cornstarch slurry, stirring constantly to prevent lumps, and let it simmer for a minute or two until thickened. Add the remaining 4 tablespoons of butter and stir constantly to incorporate …