If you don't have ground hazelnuts at home, just grind whole hazelnuts in a blender.
Now mash 2 1/2 bananas with a fork on a plate and put them in a bowl. Add all other liquid ingredients (apple cider vinegar, almond drink, coconut oil) and mix.
Add the remaining dry ingredients (spelt flour, ground hazelnuts, date sweetener, baking powder) and mix together with a hand mixer. Leave out the dark chocolate and dates for now.
Coarsely chop the dates and gently stir into the batter.
Grease a small loaf pan with coconut oil (mine measured 7.5" x 9.8" (19 x 25 cm)) and pour the batter into the pan.
Coarsely chop the chocolate and slice the remaining 1/2 banana. Decorate the dough with both.
Put it in the oven! Bake in the oven for about 30 minutes. Before you take it out, do the toothpick test to see if the banana cake is good.