• For the quark filling: Mix all the quark filling ingredients and place in the fridge until needed.
• For the plum filling: If your plum jam is overly thick, mix it with a little rum or water to soften it. Set aside until needed.
• For the streusel topping:  In a saucepan melt the butter, add flour and sugar and mix with fork until crumbly. If the mixture is too wet, add a little flour. Set aside.
• To activate the yeast: In a bowl mix together yeast and 1 teaspoon sugar. Add 4 tablespoons warm milk, mix well and sprinkle with 1 tablespoon flour. Cover with plastic wrap and let rest for 10–15 minutes.
• To make the dough: In your electric mixer bowl (or a large bowl) mix flour, sugar, milk, butter, egg yolks and salt. Add the activated yeast. Knead with dough hook (or with wooden spoon) on low speed for about 10 minutes. Cover with plastic wrap and let rise for about one hour to double its volume.
• When the dough has risen turn it onto a lightly floured surface and roll it with rolling pin to a thickness of about 1/4 inch (6mm). Cut dough into circles with 10cm (4 inch) cookie cutter or a glass (if you want small kolaches) or divide the dough into 10 equal pieces (if you want large kolaches). Reroll the scraps and cut out the last remaining circles. Press down gently on each piece with your hands to spread the dough and fill with quark filling (for the small sized kolaches, I used about 1 tablespoon of filling each). Pulling up the sides of the dough, wrap each kolach into a ‘purse’ shape.
  
• Preheat oven to 170°C (340°F). Line 2–3 baking sheets with parchment paper. Put each kolach onto a prepared baking sheet with seam side down. Gently make an indentation in the middle of each kolach with your thumb. Brush the top of the kolach with egg wash and fill the indented holes with a dollop of plum filling. Sprinkle it with streusel topping. Bake for about 20-25 minutes until golden brown.

Storage & Freezing Instructions/Tips:

• Kolaches are best the first and second day but you can store them in an airtight container in a fridge up to 5 days.