Preheat oven: Set oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
Cook cauliflower: Bring a large pot of salted water to a boil. Add cauliflower florets and cook for 5 minutes until just tender (not mushy). Drain well and pat dry with a towel to avoid excess water.
Cook bacon: In a skillet, cook bacon until crisp. Remove and crumble, reserving 1 tablespoon of bacon fat in the skillet for flavor.
Make creamy sauce: In the skillet with bacon fat, add garlic and cook for 1 minute until fragrant. Stir in cream cheese, sour cream, and heavy cream. Cook on low heat, whisking until smooth and creamy. Season with salt, pepper, and smoked paprika.
Assemble casserole: In a large bowl, combine cauliflower, half of the crumbled bacon, 1 ½ cups cheddar cheese, and the creamy sauce. Mix until evenly coated.
Bake: Transfer mixture to the prepared baking dish. Top with remaining cheddar cheese, bacon, and optional breadcrumbs. Bake uncovered for 20–25 minutes, until bubbly and golden brown.
Garnish & serve: Sprinkle with fresh chives or parsley before serving. The casserole should smell smoky and cheesy, with a lightly crisp topping and tender cauliflower inside.