Ingredients
1/2 pound poppy seeds
3/4 cup white sugar
1 tablespoon butter, melted
1 teaspoon lemon juice
1/2 cup hot milk
1 (.25 ounce) package active dry yeast
1/2 cup warm water
2 tablespoons white sugar
2 cups all-purpose flour, or more if needed
1/2 teaspoon salt
1/4 cup butter
1 egg, separated - white reserved
Directions
1. Mix poppy seeds with 3/4 cup sugar, 1 tablespoon melted butter, lemon juice, and hot milk in a bowl; stir to combine. Cover poppy seed filling and refrigerate while making bread (filling will set up and thicken as it chills).
2. Mix yeast with water and 2 tablespoons sugar in a small bowl. Allow to stand until the yeast forms a creamy layer.
3. Whisk flour with salt in a bowl; use a pastry cutter to cut 1/4 cup butter into the flour mixture until the mixture resembles coarse crumbs.
4. Pour yeast mixture and egg yolk into flour mixture and stir to make a soft dough.
5. Turn dough out onto a floured work surface and knead until smooth and slightly springy, about 5 minutes. If dough is too sticky, knead in more flour, about 2 tablespoons at a time.
6. Cut dough into 2 equal pieces. Roll each piece out into a 12x16-inch rectangle.
7. Spread half the poppy seed filling over each rectangle, leaving a 1-inch border. Fold the 1-inch border back over the filling on all sides and press down.
8. Pick up the shorter side of a dough rectangle and roll it like a jelly roll; repeat with second rectangle. Pinch ends together or tuck ends under to prevent filling from leaking out.
9. Line a baking sheet with parchment paper; place rolls seam sides down on the baking sheet and allow to rise in a warm place until doubled, about 1 hour.
10. Preheat oven to 350 degrees F (175 degrees C).
11. Beat egg white in a bowl until frothy; brush the rolls with beaten egg white.
12. Bake in preheated oven until dark golden brown on top, 30 to 40 minutes. Remove from oven and cover rolls with a clean kitchen towel until cool to keep crust soft. Cool completely before slicing.