Cook Chicken: Season chicken with salt and pepper. In batches, sear chicken in 2 tbsp olive oil over medium heat, about 5–6 mins per side. Rest and slice.
Roast or Steam Broccoli: Toss broccoli with 2 tbsp olive oil, season, and roast at 400°F for 15 mins or steam until tender-crisp.
Make Cheese Sauce: Melt butter, sauté garlic, stir in flour. Slowly whisk in stock and milk until smooth. Add salt, pepper, and cheese. Stir until thick and melty.
Assemble Bowls: Divide rice, broccoli, and chicken among 8 containers. Pour cheese sauce over top and sprinkle with extra cheddar if desired.
