Make the chocolate hazelnut cold foam: Add the heavy cream, whole milk, 1 tablespoon hazelnut syrup, malted milk powder, and cocoa powder to a small jar or container. Froth for 10-20 seconds with a milk frother, until the mixture is well combined. Set aside.
Add 1 tablespoon of hazelnut syrup to a tall glass, then stir in the cold brew coffee. Top with ice.
Top the hazelnut cold brew with the chocolate hazelnut cold foam.
Sprinkle on the crushed Oreo cookies, then drink up!