Zippy Shepherd's Pie

4 large potatoes, peeled and cubed
1 tablespoon butter
1 tablespoon finely chopped onion
1/4 cup shredded Cheddar cheese
salt and pepper to taste
5 carrots, chopped (I use canned carrots instead)
1 tablespoon vegetable oil
1 onion, chopped
1 pound ground sausage
2 tablespoons all-purpose flour
1 tablespoon ketchup
3/4 cup beef broth
1/4 cup shredded Cheddar cheese

Directions

Bring a large pot of salted water to a boil. Add potatoes and cook until tender but still firm, about 15 minutes. Drain and mash. Mix in butter, finely chopped onion and 1/4 cup shredded cheese. Season with salt and pepper to taste; set aside.
Bring a large pot of salted water to a boil. Add carrots and cook until tender but still firm, about 15 minutes. Drain, mash and set aside. (I have never has success with this step, which is why I prefer to use the canned carrots. They dont require any cooking or mashing.)
Preheat oven to 375 degrees F (190 degrees C.)
Heat oil in a large frying pan. Add onion and cook until clear. Add ground sausage and cook until well browned. Pour off excess fat, then stir in flour and cook 1 minute. Add ketchup and beef broth. Bring to a boil, reduce heat and simmer for 5 minutes.
Spread the ground beef in an even layer on the bottom of a 2 quart casserole dish. Next, spread a layer of mashed carrots. Top with the mashed potato mixture and sprinkle with remaining shredded cheese.
Bake in the preheated oven for 20 minutes, or until golden brown."