Dough:

Cup of Yum
1. Proof yeast: If using fresh yeast, crumble it in a small bowl. If using active dry yeast, place it in the bowl. Add 2 teaspoons of the already measured sugar, 2 tablespoons of the measured flour, and a little lukewarm milk from the measured milk. Just enough milk to form a thick paste. Mix well and leave to stand for about 5-10 minutes, covered, in a warm place. It should double its volume. 25 g fresh yeast / 0.9 oz OR 7 g/ 0.25 oz active dry yeast + 2 teaspoon sugar + 2 tablespoon flour + a little milk
2. Melt butter: In the meantime, melt the butter and let it cool slightly.50 g unsalted butter/ 2 oz/ scant ¼ cup
3. Combine: Place the flour into a large bowl or in the bowl of a stand mixer using the dough hooks. Add salt and the remaining sugar. Mix well. Add the lukewarm milk, melted butter, egg yolk, vanilla extract, and yeast mixture. Mix well with a spoon. 400 g all-purpose flour/ 14 oz/ 3 ⅓ cups + ¼ teaspoon fine sea salt + 30 g granulated sugar/ 2 ¼ tablespoon + 250 ml lukewarm milk/ 1 cup + 1 tablespoon + butter + 1 egg yolk + 1 teaspoon vanilla extract + yeast mix
4. Knead: with a mixer with dough hooks or stand mixer for about 5 minutes or until elastic and smooth.
5. Let rise: Place the dough in a clean bowl, cover with a kitchen cloth, and let rise in a warm place for 1 to 2 hours or until doubled in size. (Note 5)

Filling:

1. Make the filling while the dough rises.
2. Beat the egg whites until stiff.2 egg whites
3. Mix: In another bowl, mix the ground poppy seeds, raisins, blueberries, walnuts, and sugar.220 g poppy seeds/ 8 oz/ 1 ½ cups + 2 tablespoons raisins + 2 tablespoons dried blueberries + 2 tablespoons chopped walnuts + 80 g sugar/ ⅓ cup + 1 tablespoon
4. Combine: Heat the milk until boiling. Pour it over the poppy seed mixture and mix well. Set aside to cool. Fold in the egg whites.100 ml milk/ ⅓ cup + 2 tablespoons

Assemble the roll:

1. Preheat the oven to 180°C/ 350°F. Melt the butter and let it cool slightly.1 tablespoon butter
2. Roll the dough on a lightly floured surface, about 1 cm/ 0.5 inches thick and about 40x30 cm/ 15x12 inches large. Brush with the melted butter. Spread the filling on top.
3. Roll up and close the ends well so that the filling doesn't spill during baking. Then, place it on a baking tray lined with parchment paper, seam side down.
4. Egg wash: Mix the egg yolk and the milk and brush the roll with the mixture.1 egg yolk + 1 tablespoon milk
5. Bake in the preheated oven for about 45 minutes or until golden and baked through. Let cool on a wire rack.

Glaze:

1. Mix the powdered sugar with enough lemon juice (or milk or water) to form a thick, pourable glaze. Drizzle over the cooled roll. Sprinkle with a few poppy seeds if you have any left.75 g powdered sugar/ 2.5 oz/ ¾ cup + 2 to 3 tablespoons lemon juice