Here’s the technical hiccup: drinking chocolate already has sugar and often milk powder added. Cocoa powder is usually about 80-100% pure cocoa. If you swap them cup-for-cup, your brownies might turn into sugary fudge bricks. Your cake might be too wet and weirdly sweet.
But don’t panic. The cool trick is to adjust your recipe. For every cup of drinking chocolate you use, reduce the sugar in your recipe by about 2-3 tablespoons. Also, cut back on any extra dry milk or creamer the recipe calls for. You’re basically hacking the system.