Whole roasted cauliflower, aka the BEST cauliflower ever, is smothered with a creamy Dijon sauce. You're never going to look at cauliflower the same way.
Preheat oven to 375°F. Wash cauliflower head and pat dry. Trim away leaves and thick woody part of stem, being careful to leave the head of cauliflower intact.
Drizzle olive oil over the entire head of cauliflower (top, sides, and bottom) and rub it with your hands to fully coat. Sprinkle with salt and pepper.
Place in baking dish or cast iron pan and cover tightly with foil. Bake covered for 30 minutes. Remove foil and bake for another 45 minutes or until fork tender.
For the Sauce:
When cauliflower is almost finished baking, make the sauce. In a small saucepan over medium heat, whisk together cream, Dijon mustard, flour, chives, and salt. Heat, stirring constantly, until thickened, about 5 minutes. Remove from heat and whisk in butter until melted.
To Serve:
Immediately prior to serving, pour sauce over the entire cauliflower, or carefully slice the cauliflower and pour the sauce over each slice. Garnish with additional chives, if desired.
Notes
Half & half can be substituted for the heavy cream, if desired.