Preheat the oven to 400 F.
Wash Brussels sprouts, remove any outer yellow leaves and cut off brown ends. Season with salt, pepper and olive oil. Roast for 30 to 40 minutes or until vegetables are tender, giving a pan an occasional shake every 10 minutes.
In a separate small baking dish, toast the pine nuts for 2 minutes.
In a medium bowl, whisk together whole grain mustard, Dijon mustard, vinegar and honey.
Remove Brussels sprouts from the oven, transfer into a large serving bowl and drizzle over with the vinaigrette. Top with Feta cheese and sprinkle with pine nuts.