Preheat oven to 400 degrees F (205 degrees C).
Place trimmed Brussels sprouts, olive oil, kosher salt, and pepper in a large resealable plastic bag. Seal tightly, and shake to coat. Pour onto a baking sheet, lined with parchment paper, and place on center oven rack.
Roast in the preheated oven for 15 minutes, shaking (or stir) pan every and roast 10 more minutes.
Whisk together molasses and apple juice in a bowl large enough to too too sprouts, but don't toss them yet until they are pre-roasted.
Toss sprouts in marinade, and return to pan (with new parchment) using a slotted spoon to leave excess marinade behind. Roast for 15 more minutes.