• Put the butter, milk, water and sour cream in saucepan set over medium heat. Bring milk to a boil, then let cool to 130 degrees. Note, the milk will start to boil first and the butter and sour cream will start to melt and lump. You can turn off the heat at this point and insert the thermometer.
• While the milk mixture is cooling, put 2 cups (260 grams) of the bread flour, yeast, sugar and salt in a mixing bowl -- - preferably a stand mixer so you can use your dough hook. Add the milk mixture and stir until mixed, then stir in the egg. From this point, add remaining flour by quarter cups until you have a soft dough. This dough is slightly sticky, though it should be less so after kneading.
• Put the bowl on the mixer stand and knead with the dough hook until it is smooth and elastic. The dough might stick to the side of the bowl as it is being kneaded. Stop the mixer every couple of minutes and scrape side of the bowl. It will be sticky, yet still elastic and have some snap to it.
• Transfer to a bowl lightly coated in oil or melted butter. Roll it around so it is coated in the oil, then cover and let rise until doubled in bulk, about 1 hour.
• Punch dough down and turn out onto lightly floured surface. Pinch off 16 equal size portions and shape into little balls. Alternatively, you can pat the dough into a big rectangle and cut into squares if you want square kolaches. Place 8 balls (or squares) on each of two parchment lined 13x9 inch pans spacing about an inch apart. Alternatively you can do this on baking sheets. Brush with melted butter.
• Cover loosely with a greased sheet of plastic wrap and let rise for an hour.
• While rising, mix together ingredients for the topping and filling.
• Make an indentation in each risen ball and fill with about a tablespoon of cream cheese filling. Brush gently with butter and sprinkle the topping over the bun and filling.
• Preheat the oven to 400 degrees F and let the buns sit while the oven preheats.
• Bake for about 15-20 minutes at 400F. Let cool slightly before serving. The ones filled with fruit are really good hot, but the cream cheese ones are better warm or even at room temperature.

Posypka

• To make this crumb topping, mix together the flour and sugar, add a pinch of salt, then add soft butter and a splash of vanilla or a pinch of cinnamon. Stir until crumbly.

Cream Cheese Filling

• Mix together softened cream cheese and sugar, then stir in the egg yolk and lemon zest.