Pat the wings very dry and toss with baking powder, salt and garlic powder.
Arrange them in a 6-quart slow cooker and pour over 1/2 cup hot sauce mixed with 3 tablespoons melted butter.
Cover and cook on high for 2 1/2 to 3 hours until the thickest wings reach at least 165°F.
Transfer the wings to a foil-lined rimmed pan and broil 5 to 8 minutes, turning once, until browned and crisp at the edges.
Toss with the remaining hot sauce and butter, then serve immediately or hold uncovered on warm for no more than 30 minutes.