Cook spinach, covered, in a Dutch oven with 2 Tbsp. water just until limp but still bright green; drain well, pressing out excess moisture.
Transfer to a large bowl.
In a small skillet, sauté garlic in 1 Tbsp. of the butter until light brown; add remaining 3 Tbsp. butter, stirring over low heat until melted.
Pour butter-garlic mixture over spinach. Stir in Cheddar and cottage cheeses, salt and pepper.
Spoon cooked rice into an oiled 1 1/2 qt. shallow baking pan; top with spinach mixture. (Most often, I mix everything together rather than layering the rice and cheese mixture)
Bake, uncovered, at 350° F. until cheeses are melted and blended, about 15 minutes (or longer).
Cover evenly with mozzarella cheese.
Broil until cheese is melted and lightly brown, about 5 minutes.
