Place the chicken drumsticks in the slow cooker and season them with salt, black pepper, and garlic powder.
Pour 1 cup of the BBQ sauce over the drumsticks and stir to coat them evenly.
Cover and cook on low for 6 hours or on high for 3 to 4 hours until the chicken reaches an internal temperature of 165°F.
About 30 minutes before the chicken is done, preheat the oven to 400°F. Husk the corn and place the ears on a baking sheet.
Brush the corn with the melted butter and season lightly with salt and black pepper.
Roast the corn for 20 to 25 minutes, turning once, until it is tender and lightly browned in spots.
Remove the chicken from the slow cooker and brush it with the remaining 1/2 cup of BBQ sauce.
Serve the drumsticks with the roasted corn and sprinkle the parsley over the top.