Preheat the oven to 400˚F. Line a baking sheet with parchment paper and set a cooling rack inside the baking sheet. (The rack allows the bacon drippings to drip away from the Brussels sprouts and helps them to cook and crisp evenly.)
Prepare the Brussels sprouts by gently tossing them with olive oil and evenly seasoning with salt and pepper. Wrap halved bacon slices around each sprout. Arrange wrapped sprouts on the rack over the baking sheet with the bacon seam side facing down. Brush each one with maple syrup, using about ¼ cup of the syrup.
Roast for about 25-30 minutes, or until sprouts are fork tender and bacon is nicely crisped. Remove the pan from the oven and let stand about 5 minutes to cool. Bacon should crisp up even more while resting.
While the Brussels sprouts are cooling, make the dipping sauce by mixing remaining ½ cup of the maple syrup with Dijon mustard and red pepper flakes in a small serving bowl. Place sprouts on a serving platter with sauce bowl and garnish with chives. Serve with toothpicks.