Preheat the oven: Set to 375°F (190°C).
Grease a 9x13-inch baking dish with butter or olive oil.
Prep the broccoli: If using fresh, cut into small florets. Steam or microwave for 2–3 minutes until crisp-tender. If using frozen, thaw and pat dry. Dry broccoli = less watery bake.
Season the chicken: Cut into bite-size pieces or keep breasts whole if you prefer slices later.
Season generously with salt, pepper, onion powder, and smoked paprika.
Make the sauce: In a bowl, whisk softened cream cheese, heavy cream, mayonnaise, garlic, ground mustard, and a pinch of salt and pepper. Stir in 1.5 cups shredded cheddar until combined. The sauce will be thick—this is good.
Assemble: Add chicken and broccoli to the baking dish.
Pour the sauce over and toss to coat evenly. Smooth the top with a spatula.
Top it: Sprinkle the remaining 1/2 cup cheddar over the surface. For crunch, mix crushed pork rinds or almond flour with a teaspoon of melted butter and scatter on top.
Bake: Place on the middle rack for 25–30 minutes if using bite-size chicken, or 30–35 minutes for whole breasts, until the chicken reaches 165°F (74°C) and the sauce bubbles.
Brown the top: If you want extra color, broil for 1–2 minutes.
Watch closely.
Rest and serve: Let it rest 5–10 minutes to thicken. Garnish with chopped parsley or chives. Serve as is or with a crisp side salad.