Line 8 x 8-inch pan with foil, extending foil up sides of pan.
Place peanut butter and honey in microwave-safe bowl. Microwave on HIGH 1 minute. Stir. Microwave 30 seconds more until smooth and creamy.
Whisk water and powdered drink mix until blended. Stir in peanut butter mixture. Stir in granola, flax seed, walnuts and cranberries until evenly moistened.