Shepherd's Pie (Vegetarian)

1 Tbsp. olive oil
1 medium yellow onion, chopped (about 1 cup)
2 cups mushrooms, sliced
2 cups carrots, sliced
½ medium green bell pepper, chopped (about ½ cup)
2 cups crushed tomatoes
2 cloves garlic, minced
1 tsp. dried basil

Topping:
1 lb. russet potatoes, sliced into 1" rounds
¼ cup sour cream
¼ cup Parmesan cheese, grated
1 Tbsp. butter

In a large pot, heat oil over high heat. Add non; saute for 2 minutes. Add mushrooms, carrots, and bell pepper; sauté for 5 minutes. Sir in tomatoes, garlic, and basil. Reduce heat to medium; simmer, stirring frequently, until vegetables are soft, about 20 minutes.

Meanwhile, prepare topping. In a medium saucepan, combine potatoes and enough water to cover. Bring to a boil over high heat. Reduce heat to medium ad cook until potatoes are tender, about 15-20 minutes. Drain potatoes in a colander.

Preheat oven to 375°F.

In a large bowl, mash potatoes with sour cream, Parmesan cheese, and margarine until smooth.  Place vegetable mixture in a 2-quart casserole. Spread topping over vegetable mixture; smooth top.

Bake until heated through, about 15 minutes.

Serve immediately.