Preheat oven to 350°F. Line baking sheets with parchment or silicone mat, set aside. Makes 24-30 depending on size.
In a microwave safe bowl heat the butter and chocolate chips on high in 30 second increments until melted, stirring after every 30 seconds (or in a small saucepan over medium heat until melted).
In bowl of mixer, beat the melted butter/chocolate with the sugar. Add egg and vanilla and continue mixing until incorporated.
In a bowl stir together the flour, baking powder, salt, cinnamon and cayenne powder.
Add the dry ingredients to the wet in mixing bowl and stir to combine. Mixture will be slightly loose. Place bowl in refrigerator for 15 minutes to firm up the dough.
Using a scoop or measured tablespoon, drop cookie dough onto baking sheets (either keep rounded or flatten slightly if you prefer). Bake for 7-8 minutes until cookies just appear set. They will still be very soft on the inside. Don't over bake these or they will be hard. You just want a firm dense center.
In a medium saucepan combine butter, cocoa powder and milk over medium heat, whisk until blended. Remove from heat and whisk in powdered sugar.
Once the cookies are cooled, dip each into the frosting, shake excess and place on wire rack to dry (See Note 2).
Using alkalized dutch process cocoa gives the frosting a darker color and richer flavor. However, regular unsweetened cocoa powder will also work.
The frosting is quite versatile. If used right away and round cookies are dipped, there will be leftover, but I'd rather have leftover than be left without enough! I've even double-dipped for an extra coating of chocolate goodness. I also have found if I flatten the cookies instead of leaving them rounded before baking, and let the frosting firm up a little, it spreads well, too.