Preheat the oven to 180 ° C and generously grease a mini bundt pan and dust with flour. Mix flour with baking powder, cinnamon, salt and orange zest.
Beat the butter and sugar together on high speed until creamy, about 5 minutes. With the mixer running on low speed, add the eggs one at a time and vanilla. Beat on medium-high speed until combined. With the mixer running on low speed, slowly add the dry ingredients and 50 ml milk. Beat everything just until combined. But don´t over-mix. Batter will be very creamy and thick. Finally, fold in the chocolate drops.
Spoon batter into pan, best done by placing the batter in a piping bag and then squirting into the pan. Bake the minis for 20 minutes.
After baking, let cool in the pan for 10 minutes, take out and then let cool on on a wire rack.