Preheat oven to 350 degrees. Prepare a 9x13 casserole dish with nonstick cooking spray.

Place riced cauliflower in a microwave-safe container and microwave for 4 to 5 minutes until tender. Drain to remove excess moisture. Place in an even layer on the bottom of casserole dish.

In a large skillet, cook ground beef with onions over medium-high heat. Cook until ground beef browned and crumbled. Drain well and return to skillet. 

To the skillet, add tomato sauce, cumin, chili powder, garlic powder, salt and black pepper. Stir to blend and heat until bubbling. 

Meanwhile, in a medium bowl, beat eggs slightly. Add sour cream, cottage cheese, and monterey jack. Stir to blend. Spread in an even layer over cauliflower.

On top of the cheesy layer, place the ground beef sauce. Top with cheddar cheese.

Bake for 30 minutes or until the cheese on top has melted and edges are bubbly.

Top with sliced green onions and serve.