Trim the cauliflower and cut into 1/2 inch florets. Place the cauliflower in a medium bowl.
Preheat your oven to 230° F (450° F), line a large baking sheet with foil.
To the cauliflower, add 1 tablespoon of oil, 1/4 teaspoon salt, 1/4 teaspoon black pepper, and toss the cauliflower to coat.
Spread the cauliflower in a single layer on the baking sheet. Bake 25 minutes or until it is tender and lightly browned. While cooking use a spatula and turn the cauliflower.
While the cauliflower is cooking, prepare the sauce. To a medium sauce pan, add the remaining 1 tablespoon of oil and put over medium heat, when hot, add the shallots and cook 3-4 minutes or until tender and translucent, stirring often.
Add the flour, remaining 1/4 teaspoon of salt, and stir and cook 1 minute.
Add the ale, mustard, Worcestershire sauce, stir and bring to a simmer on medium high heat. Reduce heat to medium low.
Add the cheese 1/4 cup at a time and stir until smooth before adding the next 1/4 cup. After all cheese is added, keep warm, stirring occasionally, until the cauliflower is done.
Transfer the roasted cauliflower to a serving bowl or platter, top with cheese sauce. Serve as a side dish with any meal, enjoy.