Preheat the oven to 400°F (200°C). Pierce the sweet potatoes with a fork and roast for 40-50 minutes, or until fork tender. Allow them to cool slightly, then peel and mash.
Add the mashed sweet potatoes, chickpeas, rolled oats, breadcrumbs, onion, garlic, smoked paprika, cumin, onion powder, parsley, salt, and pepper to a large bowl. Mash and mix until everything is evenly combined.
If the mixture feels soft, refrigerate it for 20 minutes. This helps the patties hold their shape while cooking.
Divide the mixture into 4 equal portions and shape into burger patties about ¾-inch thick.
Place the patties on a parchment-lined baking tray. Lightly brush or spray with olive oil and bake at 400°F (200°C) for 25-30 minutes, flipping halfway through, until golden and firm.
Cook at 375°F (190°C) for 12-15 minutes, flipping halfway through.
Toast the burger buns and layer with lettuce, tomato, onion, pickles, and your favorite light sauce. Add the cooked patty and serve immediately.