Preheat the oven to 425°F. Line a baking sheet with aluminum foil.

Place cauliflower onto the baking sheet. Lightly brush each with olive oil then sprinkle with salt and pepper. Bake 20 minutes, until edges are golden brown.

While the cauliflower is in the oven, set a small saucepan on the stove over medium heat. Add the butter and when the butter is melted, pour in the wine and broth. Bring to a boil and cook for 3 minutes.

Turn the heat down to low, then add in the lemon juice, parsley, capers, mustard, and pepper. Whisk thoroughly to remove any clumps of mustard. Continue cooking for an additional 3 minutes.

Use a wide spatula to carefully transfer the cauliflower to serving plates. Spoon sauce over the cauliflower, garnish with additional parsley and serve hot.