Preheat oven to 400°F. Grease a 9x13-inch baking dish.
Sauté onion in butter over medium heat 4 to 5 minutes until soft, then add garlic and cook 30 seconds.
Steam or microwave broccoli until just tender, about 2 to 3 minutes.
In a bowl, mix soup, milk, salt, pepper, and four cheeses (cheddar, mozzarella, Monterey Jack, Colby).
Stir cooked onion, garlic, and broccoli into the sauce.
Spread mixture in the baking dish, top with tater tots in a single layer.
Sprinkle provolone and Parmesan over tots, then scatter panko on top.
Bake 30 to 35 minutes until tots are golden and cheese bubbles. Let rest 5 minutes before serving.