Classic Pot Roast with Slow Cooker (Tender Family Dinner)

Ingredients

• 1 boneless beef chuck roast, 3 1/2 to 4 lb (1.6 to 1.8 kg)
• 2 teaspoons kosher salt
• 1 teaspoon black pepper
• 1 teaspoon garlic powder
• 1 teaspoon dried thyme
• 2 tablespoons olive oil
• 1 large yellow onion, thickly sliced
• 4 large carrots, cut into 2-inch pieces
• 1 1/2 lb (680 g) Yukon gold potatoes, halved or quartered
• 4 cloves garlic, smashed
• 2 cups (480 ml) gluten-free beef broth
• 2 tablespoons tomato paste
• 1 tablespoon gluten-free Worcestershire sauce
• 1 bay leaf
• 2 tablespoons cornstarch
• 2 tablespoons cold water
• Chopped parsley, for serving