Serves: 8 mini loaves
Position the rack in the center of the oven and preheat to 175°C. Generously spray the inside of a mini-loaf baking pan with the cooking spray and set aside.
Put the butter, coffee, cocoa and milk in a small microwave-safe bowl, cover with plastic wrap and microwave on high until the butter melts, about 3 minutes. Whisk to combine.
Whisk the flour, granulated sugar, cinnamon, chile powder, baking soda, baking powder and salt in a large bowl. Beat the sour cream, eggs and vanilla in a small bowl. Whisk the hot cocoa mixture into the dry ingredients; stir in the sour cream mixture, until just combined. Divide the batter equally among the loaves, filling each about ¾ of the way. Bake until a toothpick inserted in the center comes out clean, about 30 minutes. Allow the loaves to cool in the pan on a rack for 10 minutes. Run a knife around each loaf to loosen, remove the loaves and let cool completely on a rack.
To serve, dust the tops of the loaves with confectioners' sugar. If you like, cut out small hearts or other festive stencils and place them on the loaves before dusting.