Preheat the oven to 180 °C (350 °F)
Mix flour, hazelnuts, cocoa, cinnamon, and baking powder in a bowl.
Beat the eggs and sugar with a stand mixer for 1-2 minutes to get a fluffy batter.
Add milk and oil and mix again to get a uniform mixture.
Add the dry flour mixture and fold it with a spatula, just enough for the ingredients to combine.
Add chocolate chips and gently fold in.
Pour the batter into 12 muffin molds ¾ high and bake for 15-18 minutes or until the toothpick comes out clean.
Leave to cool entirely before decorating.
Pour egg whites, sugar, and cream of tartar into a heatproof bowl and place it over a pot with simmering water (a double boiler).
Whisk for 5 minutes until the mixture becomes frothy, and all sugar is dissolved.
Add the egg whites mixture to a clean and dry bowl of a stand mixer and whisk for 5-7 minutes to get stiff peaks, the mixture is silky, and all the sugar has dissolved.
Use a round piping nozzle to decorate cooled-down cupcakes in ghost shapes.
Use chocolate chips to create eyes.
Recipe by Anja Burgar | Use your Noodles | www.useyournoodles.eu