In a large mixing bowl, combine the cream of mushroom soup, mayonnaise, 1 1/2 cups of the shredded sharp cheddar cheese, beaten eggs, milk, garlic powder, onion powder, salt, and black pepper.
Stir everything together until it forms one thick, creamy mixture. It should be spreadable but not runny; this is the rich topping that makes the casserole so comforting.
Using a spatula or the back of a spoon, spread this one thick mixture evenly over the steamed broccoli florets in the baking dish, making sure most of the broccoli is covered. This should look like a cozy blanket of sauce over the veggies.
In a small bowl, mix the crushed buttery crackers with the melted butter until the crumbs are evenly coated.
Sprinkle the buttery cracker crumbs evenly over the creamy mixture, then top with the remaining 1/2 cup shredded sharp cheddar cheese.
Bake in the preheated oven for 25–30 minutes, or until the casserole is bubbly around the edges and the top is lightly golden and crisp.
Let the casserole rest for about 5–10 minutes before serving so it can set slightly, making it easier to scoop and helping the flavors come together.
For picky eaters, chop the broccoli smaller so it blends more into the creamy layer, or mix a little of the broccoli directly into the thick soup-cheese mixture before spreading it over the rest. If your family doesn’t love sharp cheddar, use mild cheddar or a Colby-Jack blend for a gentler flavor. To add protein, stir 1–1 1/2 cups of cooked, diced chicken or ham into the thick mixture before spreading it over the broccoli. For a slightly lighter version, swap half the mayonnaise for plain Greek yogurt and use reduced-fat cheddar, keeping in mind the casserole may be a bit less rich but still satisfying. If you don’t have buttery crackers, use crushed cornflakes or panko bread crumbs tossed with the melted butter for the topping. To make it more kid-friendly, skip the garlic and onion powder and just season lightly with salt and pepper, then offer hot sauce at the table for the adults. This casserole can be assembled a day ahead: steam the broccoli, spread it in the dish, mix and spread the thick topping over the florets, cover tightly, and refrigerate. Add the crumb topping just before baking, and increase the bake time by about 5–10 minutes if going straight from the fridge.
