Heat the oven to 220 C / 425 F with a rack in the center. Line a 33 x 46 cm / 13 x 18 inch rimmed sheet pan with parchment and brush it with 1 tbsp of the oil. Cut the cauliflower into 16 to 18 florets about 4 cm / 1.5 inches wide, rinse them, and dry them thoroughly with a clean towel.
In a 3-quart / 2.8 L bowl, whisk the flour, cornstarch, garlic powder, onion powder, smoked paprika, and salt. Whisk in the oat milk until the batter is smooth and as thick as pancake batter. Add the florets and turn them with a spatula until coated, then lift each one, let the excess drip for 5 seconds, and set it on the pan 2 cm apart. Drizzle with the remaining 1 tbsp oil.
Bake for 20 minutes, flip each piece with a thin spatula, and bake 12 minutes more, until the coating is deep golden and firm when tapped.
While the wings bake, melt the butter in a 16 cm / 6-inch saucepan over low heat. Whisk in the hot sauce, maple syrup, and garlic powder, and simmer for 2 minutes, until the glaze looks glossy and slightly thickened. Keep it warm off the heat.
Move the baked wings into the empty bowl, pour over the warm glaze, and toss gently to coat. Return them to the pan and bake for 8 minutes, until the glaze turns tacky and sticky at the edges. Serve within 10 minutes.