I adapted this recipe from the "Cottage Pie" recipe at Eat at Home. It's a great easy shepherd's pie that you can have on the table in under 30 minutes. My kids all loved it (putting cheese on top helped out with that).
Easy Shepherd's Pie
1 lb ground beef
1 cup chopped onions (I used frozen chopped onions)
1 jar Heinz Home Style Savory Beef Gravy
1/4 teaspoon dried thyme
dash of dried sage
salt and pepper
1/2 - 1
2 cups instant mashed potato flakes
1/2 - 1 cup shredded cheese, optional*
Prepare instant mashed potato flakes according to package directions with the right amount of water, butter, milk, etc. (I used the Hungry Jack mashed potato flakes directions for 6 servings: 2 cups potato flakes, 1 3/4 cups water, 3 tablespoons butter, 3/4 teaspoon salt, and 1 cup milk.) Set aside.
Brown ground beef with onion. Add gravy, thyme, sage, salt and pepper, and frozen peas to the meat. Heat through and pour into a casserole or 8x11 baking dish. Top with prepared mashed potatoes using a butter knife to spread potatoes over the meat and evenly as possible. Bake at 400 degrees for 15 minutes. Sprinkle with shredded cheese and allow to cook another couple minutes to melt cheese.
*If you leave out the cheese just dot the top of the mashed potatoes with butter and sprinkle with paprika before baking.