Step 1

In a small bowl, whisk together 1½ tbsp water, vanilla, and egg white. Add the powdered peanut butter, cocoa powder, sugar, and baking powder; whisk until smooth. Stir in half of the snack bar pieces.

Step 2

Coat a 1½-cup capacity, microwave-safe mug or ramekin with cooking spray. Scrape the batter into the mug; top with the remaining snack bar pieces. Microwave on High until puffy and set, 45 seconds to 1 minute. Serve warm.

Step 3

Serving size: 1 mug cake