Preheat your oven to 375 f.
Bring a large pot of salted water to a boil, and add in your cauliflower. Blanch for 2-3 minutes, then place it into a colander to drain well.
In a large sauce pan, whisk your milk, garlic & onion powder, salt, pepper and gluten free flour, then place it on low heat. Once heated, stir in the cheddar and parmesan and stir until melted and well incorporated.
Remove from the heat.
Add your completely drained cauliflower to a baking dish and pour your cheese sauce over top, then gently stir to coat well.
Sprinkle with crumbled bacon and green onions and bake in your preheated oven until hot and bubbly, about 15-20 minutes.
Garnish with fresh chopped parsley and enjoy!