Preheat oven to 350 degrees. Spray a large casserole dish with nonstick cooking spray.
Steam cauliflower until crisp/tender; about 10 minutes. Remove from heat and set aside.
Melt 3 Tbsp butter over medium heat in a saucepan. Whisk in flour and cook for 30 seconds.
Slowly add in milk letting each addition fully incorporate before adding in more. {I work in about 1/4 cup increments}.
Bring to simmer and simmer, whisking frequently, for 5-7 minutes or until slightly thickened.
Remove from heat and whisk in cheese, salt, pepper and garlic powder. Stir in cauliflower.
Pour cauliflower mixture into prepared baking dish. Top with crumbled bacon.
In a small bowl, melt 3 Tbsp butter. Mix in panko crumbs and Italian seasoning. Sprinkle on top of bacon
Bake in oven for 20 minutes or until bubbly and lightly browned.