Preheat the oven: Set to 375°F (190°C). Lightly grease a small casserole dish (about 1–1.5 quarts).
Steam the broccoli: Microwave with a splash of water for 2–3 minutes until just tender, or blanch in boiling water for 1–2 minutes.
Drain well.
Sauté aromatics: In a skillet, melt butter over medium heat. Add onion and a pinch of salt; cook 3–4 minutes until soft. Stir in garlic for 30 seconds.
Make it creamy: Reduce heat to low.
Stir in milk, sour cream, Dijon, paprika, and half the cheddar. Warm gently until the cheese melts. Season with salt and pepper.
Combine: In a bowl, mix cooked rice, broccoli, Parmesan, and the cheesy sauce.
Taste and adjust seasoning.
Assemble: Spoon into the casserole dish. Top with remaining cheddar. Mix breadcrumbs with a teaspoon of oil (or spray) and sprinkle over the top.
Bake: 15–18 minutes until bubbly and lightly golden.
For extra color, broil 1–2 minutes, watching closely.
Rest and serve: Let sit 5 minutes so it sets slightly. Serve warm.