Before starting, preheat the oven to 450°F.Wash and dry all produce. Add 10 1/2 cups hot water and 1 tbsp salt to a large pot. (NOTE: Use same for 4 ppl.) Cover and bring to a boil over high heat. While water comes to a boil, cut cauliflower into bite-sized pieces. Thinly slice mushrooms. Thinly slice green onions.

Heat a large non-stick pan over medium-high heat. When hot, add 1 tbsp oil (dbl for 4 ppl), then beef, mushrooms and half the green onions. Cook, breaking up beef into smaller pieces, until no pink remains, 3-4 min.\*\* Season with salt and pepper.

While beef cooks, add cauliflower to the boiling water. Cook, stirring occasionally, until tender, 2-3 min. Reserve 1/3 cup cooking water (dbl for 4 ppl), then drain.

Add garlic puree and spinach to the pan. Cooking, stirring often, until spinach wilts, 1- 2 min. Remove pan from heat, then add cream cheese and reserved cooking water, then stir to combine. Add cauliflower. Season with salt and pepper, then stir to combine.

Transfer beef and cauliflower mixture to an 8x8-inch baking dish (9x13-inch for 4 ppl). Sprinkle Italian breadcrumbs and Parmesan over top. Bake in the middle of the oven, until cheese is golden-brown and melted, 5-6 min.

Divide the beef and cauliflower casserole between plates. Sprinkle remaining green onions over top.