Preheat the oven to 450F. Arrange the chicken on a baking sheet with a drizzle of olive oil, sprinkle of salt, and the rosemary. Arrange the broccoli and garlic bulb (keep the cloves together) on a separate baking sheet with olive oil and salt. Roast the broccoli, chicken, and garlic for 20 minutes, switching the pans once, until everything is cooked through and slightly browned.

When the chicken has cooled enough to handle, shred it into large pieces.

When the garlic has cooled enough to handle, make the cheese sauce. Add the butter and flour to a skillet over medium-high heat. Whisk the butter into the flour to create a roux. When the flour sizzles, slowly pour in the stock, whisking as you go, to create a smooth sauce. Add the cream, Worcestershire sauce, and ⅔ of the cheese. Squish the roasted garlic into the sauce. Stir the sauce until the cheese has melted (there may be a few lumps from the garlic, but that's ok!), and taste: add salt and pepper if you'd like.

Arrange the rice in one layer at the bottom of a 9x13 baking dish. Top with the broccoli, then the shredded chicken. Pour the roasted garlic sauce over the dish, and top with the remaining cheese.

Bake the dish for 20 minutes at 450F until the cheese is browned and bubbly.

Enjoy!