slow cooker shepherd's pie

Ingredients 

1.   1½ pounds beef chuck, trimmed and cut into 2-inch pieces
2. 2 large carrots, chopped
3. 1 large onion, chopped
4. 1 cup low-sodium beef broth
5. 1 cup dark beer (such as Guinness)
6. 3 tablespoons Worcestershire sauce
7. 2 tablespoons tomato paste
8. 2 tablespoons all-purpose flour
9. Kosher salt and black pepper
10. 2 large russet potatoes, peeled
11. 2 cups frozen peas
12. ½ cup milk
13. 2 tablespoons unsalted butter

Directions

1. Combine the beef, carrots, onion, broth, beer, Worcestershire, tomato paste, flour, 1½ teaspoons salt, and 1 teaspoon pepper in a 4- to 6-quart slow cooker. Nestle the potatoes in the liquid.
2. Cover and cook until the potatoes are tender, on low for 7 to 8 hours or on high for 4 to 5 hours. Transfer the potatoes to a medium bowl. Stir the peas into the stew, cover, and warm until heated through, 2 to 3 minutes.
3. Mash the potatoes with the milk, butter, and ½ teaspoon each salt and pepper in a medium bowl.
4. Serve the stew topped with the mashed potatoes.

http://www.realsimple.com/food-recipes/browse-all-recipes/slow-cooker-shepherds-pie