Place oats in microwave-safe container that can hold at least 4 cups. Stir in the flaxseed and salt. Whisk together the water and egg whites, pour over the oats and stir gently until just combined. Microwave on MEDIUM power for 4-6 minutes (depending on your microwave).
Remove bowl from the microwave, and stir in the peanut butter, sugar, and cinnamon. If the oatmeal becomes to stiff, soften with a small amount of milk. Serve warm.