1 pound all-purpose potatoes, peeled and quartered
1 medium head cauliflower (about 2 pounds), cored and cut into 1-inch florets
1 bunch scallions, finely chopped
1 1/4 cups low-sodium chicken broth
Kosher salt and freshly ground black pepper
1 pound lean ground beef
1 teaspoon extra-virgin olive oil
3 carrots, halved lengthwise and cut into thin half-moons
3 cloves garlic, finely chopped
2 stalks celery, finely chopped
2 medium onions, finely chopped
2 tablespoons all-purpose flour
2 tablespoons tomato paste
2 tablespoons Worcestershire sauce
One 10-ounce package frozen peas, thawed
For freezing and reheating, allow the casserole to cool completely. Divide into 6 even portions and store in a freezer-safe resealable plastic bag or container. Transfer to a microwave-safe plate, loosely cover with plastic wrap and microwave until hot, 4 to 5 minutes.