Preheat the oven to 350°F (175°C).

Sear the sliced smoked sausage in a skillet over medium-high heat until browned, about 5-7 minutes.

Melt butter in a medium pot, then sauté the diced onion until soft, around 3-4 minutes.

Add minced garlic and sauté for 30 seconds until fragrant.

Mix in the softened cream cheese until melted and smooth, then whisk in the heavy cream, and simmer until thickened, about 3-5 minutes.

Stir in the shredded cheddar cheese until completely melted, seasoning sauce with salt and pepper.

Combine the cauliflower, broccoli, and sausage in a large bowl, then pour the creamy sauce over the top.

Spread the mixture into a 9x9 baking dish and bake for 15-20 minutes until bubbly and golden.