In a microwave-safe bowl or dish, whisk together all of the ingredients. Mix until well combined. Stir in any optional add-ins if using.
Microwave on high for about 2-4 minutes. Check the oat cake after 2 minutes and add additional time if needed.
Allow the oat cake to cool for a minute or two before serving. It will firm up slightly as it cools.
Top with fresh fruit, a dollop of yogurt, or a sprinkle of cinnamon if desired!
Serve and enjoy!
