Prepare the Slow Cooker:
Lightly grease the slow cooker or spray it with non-stick cooking spray for easy cleanup.

Brown the Meatballs (Optional):
If you prefer to brown the meatballs for extra flavor, heat olive oil in a large skillet over medium heat. Brown the frozen meatballs on all sides for about 5-7 minutes. This step is optional but adds a nice texture. If skipping this step, you can add the frozen meatballs directly to the slow cooker.

Combine the Sauce Ingredients:
In a bowl, combine the onion soup mix, cream of mushroom soup, beef broth, Worcestershire sauce, garlic powder, thyme, salt, and pepper. Stir well to mix everything together.

Layer in the Slow Cooker:
Place the meatballs into the slow cooker. Pour the soup mixture evenly over the meatballs, making sure they are well-coated with the gravy mixture.

Cook:
Cover the slow cooker and set it to cook on low for 6-7 hours or high for 3-4 hours. The meatballs should be tender and the sauce should be thickened.

Serve:
Once cooked, give the sauce a stir, taste, and adjust seasoning with additional salt and pepper if needed. Serve the meatball pot roast over mashed potatoes, rice, or with crusty bread for dipping.

Garnish:
Optionally, garnish with fresh parsley or chives for a burst of color and flavor.