Turn the oven on to 400°F.

In a large bowl toss the cauliflower florets with olive oil, thyme and harissa spice, Season with salt and pepper.

Evenly spread the cauliflower out onto a non-stick baking tray.

Roast for 20-25 minutes, turning once until fork tender and slightly caramelized.

Place butter in a saucepan and melt over medium-high heat.

Reduce heat to medium and cook until a dark golden brown in color, approximately 5 minutes, remove from heat.

Stir in garlic, mustard, capers, chopped parsley and salt and pepper to taste.

Drizzle over roasted cauliflower and serve immediately.