Combine cracker crumbs and butter. Sprinkle with the cheese and remaining onions. Bake at 350 for 45 minutes to an hour or until cooked through. Sprinkle crumb mixture evenly over the casserole. Mixed Vegetable Casserole Mixed Vegetable Casserole. I used frozen mixed vegetables, 1 can cream of mushroom soup, 1 cup mayo, 1 can chopped up water chestnuts, 1 cup grated cheese, diced celery, saltines & Ritz crackers, broken up and mixed with melted butter. Yes, we ate the Mixed Vegetable Casserole down to the last crumb! Here’s the recipe. It came out great. This delightful casserole is also a great way to use up a lot of leftover veggies. Best of all, you serve one of these nutrient-rich vegetable … Vegetable casseroles have come a long way since the days of simple green beans and cheese baked in a casserole dish.Now, friends and family will look forward to the unique and mouthwatering aromas of these dishes that feature ingredients far beyond the ordinary, just like the Broccoli Cheddar Hash Brown Casserole pictured here. chopped onion, cauliflower, pepper, artichoke hearts, broccoli sprouts and 7 more. Sprinkle crumbs over top of the Mixed Vegetable Casserole. Cover with foil if crackers start to get too brown. Bake at 400 degrees F for 20 minutes or until the vegetable mixture is hot and bubbling. Rating: 4.38 stars 105 Ratings. Stir the vegetable mixture. Stir well. … I had to substitute several ingedients, as I didn’t have everything to do it ‘Taste of southern’ specifics.