Slow Cooker Mushroom Pot Roast

Name: Slow Cooker Mushroom Pot Roast
Ingredients: 1 ounce dried mushrooms, ground into a coarse powder; 2 tablespoons dijon mustard; 2 tablespoons white miso paste; 2 tablespoons cheese, grated; 4 cloves garlic, minced or grated; 1 teaspoon thyme, chopped; 1 tablespoon Worcestershire sauce; 2 teaspoons black pepper, coarsely ground; 1 (4 pound) beef roast (such as chuck, eye of round, etc.); 2 pounds mushrooms, sliced or quartered; 1 onions, sliced; 1 pound carrots, cut into bite sized pieces (optional); 1 pound potatoes, cut into bite sized pieces (optional); 1/2 cup beef broth; 2 tablespoons cornstarch + 2 tablespoons water