Preheat the oven on to 425ºF and lightly oil a 9 x 13" baking dish.
Boil a medium pot of water (with a steamer lid) and steam cauliflower florets with 4 cloves of garlic.
Once cauliflower is well cooked (a knife inserted in cauliflower should slip easily) about 5-8 minutes, transfer 1/2 the cauliflower to a blender along with steamed garlic cloves. Add half the grated cheddar to blender and a pinch of salt & pepper to taste. Blend well.
Meanwhile, use remaining boiling water to cook penne (about 10 minutes). Steam broccoli over the boiling pot.
Remove steamed broccoli and rinse with cold water to blanch. Strained penne in a separate colander.
In the oiled baking dish, mix in penne, broccoli and cheese sauce until everything is well coated. Sprinkle remaining cheddar and parmesan evenly across the top.
Bake dish in oven until cooked and cheese is golden (about 35 minutes). Remove from heat and let sit to cool. Serve and enjoy.