Meanwhile, spread cookies and pretzels in single layer, right side up, in remaining pan. In same microwavable bowl, microwave remaining 1/2 cup baking chips uncovered on High 30 to 60 seconds, stirring after 30 seconds, until chips are melted and smooth. Transfer melted chips to small resealable food-storage plastic bag, and cut small corner off one end of bag. Drizzle onto cookies and pretzels; sprinkle with nonpareils. Cool 20 to 30 minutes or until set.