Place the quark or cottage cheese in a small sieve over a bowl to drain. Set aside. Mix the rum, currants, raisins and candied peel in a small bowl. Stir to combine and set aside to soak.
Preheat the oven to 325F. Line a large baking sheet with parchment paper or silicone baking mat and set aside.
In a large bowl, mix together the flour, baking powder, baking soda, cardamom, nutmeg, salt and sugar until evenly combined. If you are using cottage cheese, pour out any liquid that has drained into the bowl, then press the cheese through the sieve using a spoon or spatula. Cut the butter into small pieces, then add it along with the egg, vanilla extract, lemon zest, almonds, dried fruit including any rum in the bottom of the bowl and the drained quark or cottage cheese to the dry ingredients. Mix everything together with your hands until evenly incorporated into a sticky dough.
Scrape the dough together with a flexible dough scraper or a spatula, then empty it onto the prepared baking sheet. Flatten it and form it into a rectangle about 12" long and 6" side. Fold one long edge about 2/3 of the way over top to give it that traditional stollen shape.
Bake for 45 minutes or until deep brown on top and a toothpick poked in the centre comes out clean. While the stollen is baking, melt the butter.
Remove the stollen from the oven, brush it with the melted butter and dust with icing sugar. Let cool. Before slicing and serving, dust with additional icing sugar.