Begin by heating the oven to 350°F and spraying a large baking dish with cooking spray. Then using a cheese grater or food processor, grate the cauliflower and set aside. Next, cook the bacon using your preferred method. Then transfer to a paper towel-lined plate to drain.
In a large bowl, whisk the eggs, milk, garlic, paprika, salt, and pepper together until combined. Next, place the cauliflower in the baking dish and top with cheddar, bacon, and green onions before pouring the egg mixture over the top.
Place the dish in the oven and bake for about 35 minutes or until the casserole is set and the top is golden and bubbly. Garnish with more green onions if desired and serve!