Spray a 9x13 casserole dish with cooking spray.
If using fresh broccoli, steam or blanch it until fork-tender (see post). If using frozen broccoli, thaw, and drain.
Add the butter and oil to a saucepan over medium heat. When the butter is melted, add the onions and garlic; cook for 3-4 minutes or until softened.
Stir in the flour and cook for 1 minute. Whisk in the chicken broth and reduce the heat to low.
Add the cream cheese and cook, stirring frequently, until melted. Stir in the Worcestershire sauce.
Add the cheddar cheese and stir until fully melted. Stir in the cauliflower rice.
Add the broccoli to the prepared baking dish. Pour the cheese sauce over the broccoli; top with the cracker crumbs.
Bake at 350°F for 45 minutes. If desired, broil the casserole for 5 minutes for a crispier topping.