2T Extra-Virgin Olive Oil
3T Unsalted Butter
1 Medium Onion, diced
3c Green Beans
1 Zucchini, sliced and halved
1/2lb. Cremini Mushrooms, quartered
2 cloves Garlic, minced
1T Kosher Salt
3/4t Dried Oregano
3T Tomato Paste
1lb. Ground Beef
1/4c can low-sodium Beef Broth
1/2t Worcestershire Sauce
Freshly Ground Black Pepper
4 cups Mashed Potatoes
1/4 cup grated Parmesan, optional
Preheat oven to 375 degrees F.
Heat the olive oil and 2T of the butter in a large skillet over medium heat. Add the onion, g. beans, zucchini, mushrooms, garlic, half the salt, and oregano. Cook until vegetables are tender, about 10 minutes. Stir in the tomato paste and cook until mushrooms are soft and tomato paste has turned brick red, about 8 minutes more. Stir in the beef, the broth, the remaining salt, the Worcestershire, and some pepper, breaking up any large clumps of meat, cook until the meat is no longer pink, about 3 minutes.
Transfer the meat and vegetables to a 2-quart oval casserole dish and spread the mashed potatoes over the top, leaving a 1/4-inch boarder around the edge. Make a decorative pattern on the top of the potatoes, if desired. Sprinkle with cheese, if using, and dot with the remaining tablespoon of butter. Bake until potatoes brown and the juices bubble around the edge, about 40 minutes. Let cool for 10 minutes before serving.