1. Place the beef cubes in a large slow cooker. Top with the garlic, carrots, mushrooms and corn.
2. In a medium bowl, whisk together the beef broth, tomato paste, Worcestershire sauce, oregano and House Seasoning.
3. Pour the broth mixture over the contents of the slow cooker and stir to combine.
4. Cover the slow cooker and cook on low for 7 to 9 hours, or on high for 3 1/2 to 4 1/2 hours, until the beef is tender.
3. Reduce the heat and simmer until the potatoes are tender when stabbed with a fork (start checking them at 15 minutes).
4. Drain the potatoes, and return them to the pot.
5. Add the milk, butter, salt and pepper, to taste.
8. In a small bowl, mix the flour and 6 tablespoons water until smooth, then slowly stir the mixture into the slow cooker. Add the peas. Adjust the seasonings to taste with salt and pepper.
9. Mix the cheddar cheese into the mashed potatoes and spread in an even layer over the top of the beef and vegetables.