Preheat oven to 400°.
Clean cauliflower and cut the center bottom to remove the stem and leaf parts.
Dice cauliflower into chunks and put into a large pot. Fill pot with water to cover the cauliflower.
Top with fresh cracked salt and pepper.
Cover pot with lid and boil cauliflower for about 25 minutes until tender.
Drain in a colander.
Cook rice according to package instructions.
Mince garlic and set aside.
Mince shallot and set aside.
Add butter to skillet over medium heat, then add shallots.
Sauté for a few minutes, then add garlic. Sauté for another minute.
Add flour and whisk for 1 minute.
Slowly pour in milk and whisk until no clumps. Turn heat to low to let sauce thicken.
Add in spices and gruyere cheese until melted.
In a large bowl, mix cooked cauliflower, cooked rice, mushrooms, and cheese sauce. Mix well.
Spray 9x9 baking dish with cooking spray and pour in cauliflower mixture into dish. Spread to even layer.
Top with breadcrumbs and parmesan cheese
Cook for 20 minutes.
Garnish with fresh parsley.