Roasted Broccoli Cheddar Casserole

I love broccoli casserole.  When I saw this recipe I was totally intrigued by this version from Neighborfood.  I adapted it slightly to our taste.  It was so cheesy and delicious.

4 cups broccoli florets
2 tbsp olive oil
salt and pepper
3 tbsp butter
3 tbsp flour
1 1/4 cup milk
1 1/2 cups shredded cheddar cheese
1 sleeve ritz crackers (crushed)
2 tbsp butter

Toss the broccoli in olive oil, salt and pepper.  Spread out on a pan and roast for 15-20 minutes at 400 degrees.  While the broccoli is roasting melt the better in a medium sauce plan. Whisk in the flour and let cook for 2 minutes.  Whisk in the milk and bring to a simmer.  When the mixture begins to thicken remove from heat and stir in cheddar. Place the broccoli in the bottom of a casserole dish.  Pour the cheddar sauce over the broccoli.  Sprinkle with the crackers then thinly slice the butter and layer on top of the crackers. Bake in the oven for 15 minutes.