Preheat oven to 410°F (210°C) and cut the sweet potato into ¾ inch (2cm) pieces. Place it in an ovenproof dish, drizzle with ½ tbsp. olive oil and season with salt & pepper, rosemary, and chili flakes. Bake for 25-30 minutes.
Once potatoes are cooked, allow them to cool slightly. Then peel off the skin, place in a bowl, and mash the flesh with a fork. Add in the drained beans and also mash with a fork.
Cook quinoa according to instructions on the packaging. Once cooked, transfer to the mashed beans and potato, season with salt & pepper, and mix well.
Using slightly wet hands, form 4 burgers and grease each one with the remaining olive oil. Place on a baking tray lined with tin foil and bake for 20-25 minutes in 410°F (210°C).