Preheat oven to 350 degrees Fahrenheit. Grease a 9×13-inch baking dish.

Squeeze liquid out of thawed spinach.

Saute the onion, celery and mushrooms in the margarine for about 10 minutes, stirring often. Put the mixture into a large bowl.

Add the carrots, matzo meal, spinach, eggs and salt and pepper. Mix well.

Pour into the greased casserole dish. Bake for 40 to 45 minutes, until firm.