Add the cream, milk, and butter to a medium-size saucepan. Warm over medium heat, whisking occasionally, until melted.
Stir in the remaining ingredients (cheese, garlic, salt, pepper), and whisk until the cheese is melted.
Let the sauce thicken slightly over medium-low heat, stirring occasionally. Do not boil.
Assemble the Casserole:
Preheat the oven to 350F and grease a casserole dish.
Chop the broccoli florets no larger than 1” pieces (or use pre-chopped frozen broccoli). Set aside in a large mixing bowl.
Dice the chicken in 1” cubes; season with salt, pepper, and paprika and add to the bowl.
Add the uncooked rice and chicken broth to the bowl. Pour the prepared alfredo sauce into the bowl as well. Stir to combine.
Pour the mixture into the greased pan and cover tightly with foil or a lid. It must be sealed tightly for the rice to cook through.
Bake, covered, for 45 minutes.
While baking, prepare the topping (if using). Add the panko, butter, and seasoning (oregano, paprika, salt) to a medium-size skillet (use the same skillet from making the sauce, just rinse it off). Saute over medium heat, stirring, until nicely browned. Do not burn.
Remove the casserole from the oven and uncover. Top with the prepared panko and shredded parmesan. Return to the oven, uncovered, for 10 minutes.