In a large bowl, toss brussels sprouts with avocado oil, about 2 tablespoons.
Pour brussels sprouts onto a large jelly roll pan and shake the pan to get the brussels sprouts to be in an even layer.
Bake for 25 minutes, turning the brussels sprouts with a spatula halfway through the cooking process.
Remove from oven and place back into large bowl and pour pistachio pesto on top and toss together until brussels sprouts are coated. The warmth of the roasted brussels sprouts will help the pistachio pesto coat the sprouts.
Sprinkle with more chopped pistachios, if desired.