Melt the butter in warm milk (don't make it too hot!).
Add the remaining ingredients and knead the dough (using your hands or food processor). The dough may be a bit sticky but it's ok.
Place the dough in a big bowl then cover it with a clean kitchen cloth.
Leave the bowl in a warm place for about 90 minutes until the dough doubles its size.
If your poppy seeds are not ground, grind them in a coffee/meat grinder or food processor. You may need to run the food processor a few times, depending on how strong your grinder is.
Bring the milk to almost boil.
Add poppy seeds to boiling milk, and cook for about 2 minutes, stirring all the time.
Add sugar, and butter to hot poppy seeds and mix.
Add chopped nuts/dried fruits and mix again. Allow to cool.
Beat the egg whites with a bit of salt until stiff.
Carefully add beaten egg whites to the poppy seeds.
Preheat the oven to 350°F / 175°C.
Divide the dough into 2 pieces.
Roll each piece out onto a floured surface to just under ½” thickness.
Spread the filling onto the dough, avoiding the edges.
Roll up the pastry, starting at one of the long ends. Make sure to tuck the ends of the roll under it. (that will prevent the filling from leaking out).
Brush the rolls with beaten egg or melted butter.
Place the poppy seed rolls on a pan lined with baking paper.
Bake for 35-40 minutes.
