Preheat the oven to 400 degrees.
Heat the oil in a large nonstick skillet over medium heat and coat with cooking spray. Flick water into the skillet and if it sizzles, it’s ready. Add in the sweet potato noodles and season with salt, pepper, and garlic powder. Cover and cook, uncovering to toss occasionally, for 5-7 minutes or until noodles are softened and lightly browned.
Transfer the cooked sweet potato noodles in a medium bowl, allow to cool for 1-2 minutes, then add in the eggs. Toss to coat.
Fill four 6-ounce ramekins halfway with the noodles. Cover each with a piece of foil or parchment paper and push it so that it’s directly touching the noodles. Place a can or similar heavy item over the foil and press firmly to compress. Refrigerate at least 15 minutes so that the noodles set.
While the buns set in the refrigerator, prepare the black bean mixture. Heat the oil in a large skillet over medium-high heat. Once oil is shimmering, add the corn, black beans, tomato, chili powder, cumin, oregano and cook for 5 minutes or until everything is heated through and onions soften. Set the mixture aside in a plate or bowl.
When noodles have set, heat 1 tablespoon of olive oil in the same skillet used to cook the bean mixture. Once the oil is shimmering, add in all of the buns, flipping each ramekin over the skillet and patting the bottom until the bun falls out.
Cook for 5 minutes or until noodles set, being sure to push in any stray noodles. Then, carefully flip and cook another 5 minutes or until the bun is completely set and browned, flattening with the back of the spatula.
While buns cook, line a small baking sheet with parchment paper. Once the buns are done, transfer them to a baking sheet and spread at least two inches apart. Smear each bun with about 1 tablespoon of the barbecue sauce. Top with black bean mixture and then top with about 2 tablespoons of cheese per bun. Place in the oven and let cook for 5 minutes or until cheese melts.
Immediately garnish with olives and serve with an avocado slice.