If you're using cottage cheese, press it through a sieve or blend it briefly in a food processor until fine.
Grease a loaf pan and preheat the oven to 325 degrees F.
In the bowl of a stand mixer with the paddle attachment or in a large bowl with a hand mixer beat the butter, then add the sugar and beat until smooth. Add the egg and almond extract and beat again until fluffy. Fold in the ground hazelnuts until completely incorporated. Set aside.
In a medium bowl, mix together the flour and baking powder with a whisk. Pour this onto a large, clean area of countertop and make a well in the middle. Add the sugar, vanilla extract, lemon extract, rum and the egg into the well. Cut the cold butter into small pieces and distribute it around the outside of the flour along with the quark or cottage cheese.
Using your hands, mix the sugar, flavourings and egg with some of the flour to create a thick consistency. Then work everything together into a smooth dough. If the dough is sticky, add a touch more flour to the counter and mix it into the dough. Move the dough to the side.
Lightly flour the countertop and the top of the dough. Roll the dough out into a rectangle the width of the loaf tin until it is 1/2" thick. Use additional light dustings of flour as needed to keep the dough from sticking to the countertop and the rolling pin.
Drop large spoonfuls of the hazelnut filling over the dough and then spread it to the edges evenly. Roll up the dough and place into the loaf pan with the seam side down. Make two cuts the entire length of the dough approximately 1cm deep (through to the first layer of nut filling).
Whisk the egg and milk or cream together for the egg wash. Spread it generously over the top of the dough without letting it dribble down into the sides of the loaf pan.
Bake for 60 minutes, remove and brush with egg wash again. Bake for another 10 minutes or until the top is a deep golden brown and a toothpick poked into the centre comes out clean.
Drag a sharp knife around between the bread and the loaf tin, then turn upside down to remove. Place on a wire rack to cool.
In a double boiler or in a small bowl on top of a small pot with a little water in it, melt the chocolate and coconut oil over medium-low heat until smooth. Use a spoon or spatula to drizzle it over the bread.