Preheat oven at 400 degrees
First make the Dijon dressing by combining all the above ingredients.
Now, Boil the whole cauliflower for 5 minutes in salted water. Then pat dry.
Next take the cauliflower (leaving it whole) place on sheet tray.
Salt generously the whole cauliflower (make sure to season bottom and inside too).
Now pour 3 tbsp olive oil all over the cauliflower.
Next pour 2/3 of dressing all over the cauliflower. Brush to cover all over.
Place 2 tbsp of butter under the cauliflower.
Place in the oven for 50 minutes.
Finally take out of oven and pour rest of Dijon mustard, parsley, and dill on top.
Slice up and enjoy!