Place oats in microwave-safe bowl (at least 4-cup capacity). Add egg white or whole egg to oats. Stir to combine (no specks of yolk should show if using whole egg). Add milk; stir until all ingredients are well combined. For quick oats, microwave on HIGH, uncovered, 2 to 2-1/2 minutes or until egg is fully cooked and oats are desired consistency. For old fashioned oats, microwave on HIGH, uncovered, 2 minutes. Stir oats, microwave about 1 minute longer in 30 second intervals, stirring after each interval until egg and oats are cooked. Let stand 1 to 2 minutes if thicker consistency is desired. Top with yogurt and pistachios. Drizzle with honey.
Cook Note: Recipe tested in 1100-watt microwave oven.