Meitschibei (Swiss Horseshoe-Shaped Pastries)

To make the dough:

1. In a small bowl, sprinkle the yeast over the lukewarm milk, stirring briefly to combine. Allow to sit at room temperature until frothy, 5-10 minutes.
2. In the bowl of a stand mixer fitted with a dough hook or a large bowl, combine the flour, sugar, and salt.
3. Mix in the frothy yeast with milk and the butter until a dough comes together. If still too dry, add a little more milk. If too sticky to handle, add a little more flour.
4. On a lightly floured surface, knead until smooth and elastic. Oil a large bowl and add the dough, turning to coat. Cover with plastic wrap or a towel and allow to rise at room temperature until doubled, about 1 hour.

To prepare the filling:

1. In a large food processor, pulse together the hazelnuts, sugar, cinnamon, lemon zest, and salt.
2. Once finely chopped and well combined, slowly add just enough water to hold together the mixture with the consistency of thick paste. Do not add too much water or the mixture may become too loose.

To assemble the pastries:

1. Separate the egg into an egg white in one small bowl and egg yolk in another small bowl. Add the 1 tablespoon (15 milliliters) milk to the egg yolk.
2. Line two baking sheets with parchment or lightly grease.
3. On a lightly floured surface, roll the dough into a thin sheet about 20 inches (51 centimeters) long and 18 inches (46 centimeters) wide.
4. Cut the dough in half lengthwise to make two 9 inch (23 centimeter) wide rectangles.
5. Cut each rectangle crosswise every 3 inches (7.5 centimeters) to make 12 strips in all.
6. Add a thin rope of filling across the center of one of the strips, keeping about 1/2 inch (1.5 centimeters) clear around the edge.
7. Brush the edges with the egg white. Bring up the edges over the filling, pinching together to seal.
8. Gently roll the pastry to lightly stretch into a filled rope about 12 inches (30.5 centimeters) long and to completely seal.
9. Fold the rope in half to form a horseshoe and place on the prepared baking sheet.
10. Repeat with remaining dough and filling, placing 2 inches (5 centimeters) apart on the baking sheets.
11. Cover the baking sheets with towels and allow to rest at room temperature until lightly puffed, about 30 minutes.
12. Preheat oven to 350˚F (180˚C).
13. Brush the tops of the pastries with the egg yolk milk mixture.
14. Bake in preheated oven until golden on the top, 15-20 minutes. Serve warm from the oven or at room temperature.