3 pounds potatoes, such as russet, peeled and cubed
2 tablespoons Greek yogurt
1/2 cup chicken broth
1 tablespoon butter
1/2 cup skim milk
sea salt and freshly ground black pepper
1 tablespoon extra-virgin olive oil
1 3/4 pounds extra-lean ground beef, (or lamb, if desired)
1 teaspoon garlic, minced
1 12 oz.bag frozen peas and carrots, cooked according to package directions
1 onion, chopped
2 stalks celery, chopped
4 tablespoons butter
4 tablespoons all-purpose flour
2 cups chicken broth or beef broth
2 teaspoons Worcestershire
1 teaspoon paprika
1/2 cup shredded cheddar cheese