Melt butter in a dutch oven. Saute garlic and chopped onion until fragrant for about 2 minutes.
Pre-heat oven to 400ºF
Add flour and saute for a minute. Take care not to burn the flour.
Slowly stir in the chicken stock to avoid any lumps. Then stir in milk to make a smooth mixture.
Add in dijon mixture, thyme, pepper, salt, and sour cream. Whisk well.
To the creamy sauce, add cooked rice, blanched broccoli, diced ham, and 2 cups of shredded cheese ( reserve 1 cup for later).
Shift the mixture to a 9X13 baking dish. Sprinkle the remaining shredded cheese.
In a small bowl, mix breadcrumbs and melted butter.
Sprinkle breadcrumb topping all over the cheese. Bake for 30-35 minutes, until the breadcrumb topping is crispy and brown and the cheese underneath is bubbly.
Video
Notes
Instead of sour cream, use heavy cream and add an extra 1/2- 1 teaspoon dijon mustard.
If the rice mixture looks too dry then add an extra 1/2 cup chicken stock. The last thing you want is dry casserole