Cut a thin slice from the stem end of each sprout, but don't cut off the stem completely. Keeping the stem intact helps keep the brussels sprouts in one piece while cooking.
Place the brussels sprouts in a large pot, and cover with cool water. Bring to a boil over high heat (it will take about 10 minutes to reach a boil). Reduce heat to medium-low and cook until the brussels sprouts are tender through when pierced with a knife, about 14 to 18 minutes (just test a couple of them).
Give them a good drain and pat them dry with a paper towel.
Line a baking sheet with parchment paper, set aside.
Preheat the oven to 425°F/220°C. Transfer the brussels sprouts to the baking sheet.
Use the bottom of a glass to smash the brussels sprouts so they’re flat and let them rest on the pan for 5 minutes to release the steam.
Brush the brussels sprouts with oil and sprinkle with salt, pepper, and garlic powder.
Bake until crispy for 30 to 40, flipping halfway through.
While the brussels sprouts are roasting, whisk together all the dipping ingredients.
When the brussels sprouts are done, serve immediately with the dip on the side.