Preheat and prep: Preheat the oven to 190°C/375°F. This moderate temperature allows the casserole to cook through without drying out the chicken and gives the top time to brown gently.

Cook the rice: Rinse 185 g (1 cup) long-grain white rice under cold water until the water runs clear to remove excess surface starch (this keeps the cooked grains separate). Combine rice with 375 ml water and a pinch of salt in a medium saucepan, bring to a boil, then reduce to a low simmer, cover and cook 15 minutes until tender. Remove from heat and let sit covered for 5 minutes. Cooking the rice separately guarantees you control its texture so the casserole isn’t gummy.

Par-cook the potatoes: While rice cooks, peel (if you prefer) and cut potatoes into 1–1.5 cm (3/4 inch) cubes for even cooking. Put them in a pot, cover with cold salted water, bring to a simmer and cook 6–8 minutes until just fork-tender but not falling apart. Drain and set aside. Par-cooking ensures the potatoes finish perfectly in the oven without over-baking the chicken.

Season and sear the chicken: Pat 1000 g chicken breasts dry, then season both sides with 1 tsp salt, 1/2 tsp pepper, 1/2 tsp paprika and 1/2 tsp dried thyme. Heat 2 tbsp (30 ml) oil in a large skillet over medium-high heat until shimmering. Sear chicken 2–3 minutes per side until golden (it will not be fully cooked). Searing develops Maillard flavors that give the casserole depth. Transfer chicken to a plate and let rest 5 minutes, then cut into bite-sized pieces.

Sauté aromatics: In the same skillet, reduce heat to medium and add 1 tbsp (14 g) butter. Add the diced 110 g onion and 9 g garlic and cook 3–4 minutes until softened and fragrant. Scrape the browned bits from the pan — they are concentrated flavor you want in your sauce.

Make a roux-based cream sauce: Add the remaining 42 g butter to the skillet. Sprinkle 24 g (3 tbsp) flour over the melted butter and whisk for 1 minute to cook the raw flour taste and build a roux (this thickener gives the casserole a silky coating). Slowly whisk in 480 ml whole milk and 240 ml chicken stock, a little at a time, then bring to a gentle simmer. The sauce will thicken as the flour gelatinizes; simmer 3–5 minutes to reach a thick, velvety consistency. Taste and season with 1 tsp salt (adjust down if your stock is salty), 1/2 tsp black pepper, remaining 1/2 tsp thyme and remaining 1/2 tsp paprika.

Combine components: In a large bowl or the empty (cleaned) skillet, combine the cooked rice, par-cooked potatoes, seared chicken pieces and the cream sauce. Fold gently to coat — you want the grains preserved, not mashed. The sauce should bind everything without swimming in liquid; it will firm slightly as it bakes.

Transfer to baking dish: Lightly butter a 9x13-inch (23x33 cm) casserole dish or equivalent. Spoon the mixture into the dish, smoothing the top so the potatoes arrange in a single-ish layer. Dot the surface with a few small pieces of butter (from the 4 tbsp used) for a golden finish when baked.

Bake: Cover the casserole with foil and bake at 190°C/375°F for 25 minutes to allow flavors to meld and the center to heat through. Removing air contact early prevents a dry crust and gives time for interior steaming.

Brown the top: Remove the foil, increase oven to 200–220°C/400–425°F (or switch to broil for the last step) and bake uncovered 10–15 minutes more, or broil 2–4 minutes until the top is golden and bubbling. This final blast of heat caramelizes the surface and gives a satisfying contrast to the creamy interior. Watch closely under the broiler to avoid burning.

Rest and garnish: Let the casserole rest 8–10 minutes before serving. Resting lets the sauce set slightly so slices hold together. Sprinkle with chopped fresh parsley for color and a fresh herb lift.

Serve: Scoop generous portions (about 1/6 of the dish) onto warm plates. Recommend serving with a simple green salad or quick sautéed greens to cut the richness.