Step 1 Make the Ultimate Keto Buns by following the video recipe. They will be darker in color if you use brown flax, or light in color if you use golden flax. You can make a double batch of keto buns and keep them in the freezer. When you want to make the burgers, let the buns defrost at room temperature. Optionally, you can cut the buns in half and briefly crisp up under a broiler.