Blend all together and let sit in fridge; overnight is best. You want this mixture thick like a can of cream of chicken soup. Make sure if using blender to not overmix and make butter with your heavy cream.
Preheat oven to 350 degrees. Cook chicken thighs in the remaining 2 oz of chicken broth. A pressure cooker (such as an InstantPot) can be used; thawed chicken, 20 min poultry setting. Add more liquid if needed. Remove chicken and shred the meat, discarding as much liquid as possible.
Place steamed and well-drained broccoli in bottom of 9x13 pan. In a large bowl, mix shredded meat, riced cauliflower, 1 cup of the shredded cheese, onion, garlic, onion powder, salt, pepper, and your cream of chicken replacement.
Test for flavor and add more salt if desired. Once happy with the flavor, pour chicken mixture over top of broccoli. Top with remaining 1 cup of cheese.
Bake at 350 degrees for 20-30 mins.
I steamed the broccoli and cauliflower the night before, placed paper towels in their own colander, and let them drain overnight into separate bowls. This seemed to work well to minimize extra liquid. Make sure you add extra salt and onion powder if you enjoy those flavors. I also add extra garlic to make it delicious. Bone-in, skin-on chicken thighs worked well for this recipe and shredded easily after being cooked in my InstantPot. This recipe can be frozen! Thaw before baking, and bake a bit longer until cheese is bubbly.