1. In a food processor fitted with a grater attachment (or using a handheld box-grater), finely grate beets and red onion. Transfer to a fine-mesh strainer or cheese cloth and press out as much excess liquid as possible. Transfer to a large bowl. Add rolled oats, garlic, and rosemary and (using hands), thoroughly combine. Set aside.
2. In a high speed blender or food process fitted with an S blade, process cannellini beans and walnuts until very smooth. Scoop into large bowl with beet mixture, then using your hands, thoroughly combine. Form mixture into 8 even balls, then flatten until about 1 inch thick patties. Allow patties to sit for about 30 minutes, allowing the oats to absorb some of the moisture.
3. Preheat oven to 350 degrees F, rack in the middle. Line a baking sheet with foil and lightly grease with olive oil. Bake patties for 15 minutes, flipping gently after 5 minutes. Remove from oven.
4. Preheat 1 tablespoon olive oil over medium-high heat in a non-stick skillet. Add 2 patties to pan and cook for 2 minutes. Gently flip and cook for an additional 2 minutes. Remove from heat, then repeat (adding 1 tbs. oil per 2 burgers) for the remaining 6 patties. Enjoy!
Recipe Source: In My Bowl