Walnut and poppy seed beigli from Hungary

I'm addicted! I just had three slices of this. So delicious! It's also very good after freezing, so I don't have to eat all of it at once.

Ingredients
300g flour
100 g softened butter
2 eggs
2 tsp yeast
40mL milk
0.5 tbsp icing sugar
1/3 cup sour cream
pinch of salt

poppy seed filling:
200g ground poppy seeds
200g sugar
juice and grated peel of one lemon
1 tbsp butter
0.5 cup milk
1 grated apple

walnut filling:
300g ground walnuts
200g sugar
0.25 cup milk
1 tsp vanilla
1 tsp grated lemon peel
1 grated apple

Preparation
Mix the butter and flour. Bloom the yeast in the lukewarm milk and 1 tbsp sugar. Add it to the flour and butter mix, then add the remaining ingredients. Mix until smooth, add a bit more flour if necessary. Cut into two, and refrigerate for half an hour.

Decide if you like poppy seeds or walnuts more, and make the chosen filling. Bring the liquid portion to a boil, mix in the solids and simmer for five minutes. Cool the filling.

Roll out the dough to a rectangular shape about 1/8 inch thick. Spread the filling on it, leaving some space free around the edges. Roll up the dough, press closed and place on a baking sheet seam-side down. Brush with egg wash a few times, waiting a few minutes in between repeats.

Puncture with a fork at a few places to allow the release of steam. Bake 30-40 minutes in a preheated 350F oven, until golden brown.