Creating this Hearty Slow Cooker Beef Casserole is a breeze when you follow these simple steps:

1. Prepare the Beef: In a large bowl, season the beef cubes with salt and pepper.
2. Brown the Beef (optional): In a skillet, heat a bit of oil over medium heat. Brown the beef cubes on all sides for added flavor. Transfer to the slow cooker.
3. Add Vegetables: Layer the chopped onions, carrots, and potatoes over the beef in the slow cooker.
4. Mix the Sauce: In a separate bowl, combine the beef broth, diced tomatoes, tomato paste, Worcestershire sauce, thyme, and rosemary. Stir well.
5. Pour the Sauce: Pour the sauce mixture over the beef and vegetables in the slow cooker.
6. Cook: Cover and cook on low for 6 to 8 hours or on high for 4 to 5 hours until the beef is tender.
7. Add Peas: In the last 30 minutes of cooking, add the frozen peas to the slow cooker and stir gently.
8. Check for Seasoning: Before serving, taste and adjust seasoning, adding more salt and pepper if desired.
9. Serve: Ladle the casserole into bowls and enjoy the hearty goodness!

These straightforward steps will guide you in creating this incredible meal effortlessly.