Preheat the oven to 375 degrees. Toss the corn kernels and chopped bell peppers with the olive oil on a baking sheet. Roast for 15 minutes, then remove and let cool slightly.
In a large bowl, combine the ground beef, egg, 1/4 cup BBQ sauce, smoked paprika, onion powder, salt, black pepper, and diced onion. Add the roasted corn and peppers.
Mix everything together with your hands until just combined. Shape the mixture into a loaf and place it on a baking sheet lined with parchment paper.
Bake for 35 minutes. Remove from the oven, spread the remaining 1/4 cup BBQ sauce over the top, and return to the oven for 10 more minutes.
Let the meatloaf rest for 5 minutes before slicing and serving.