In a medium saucepan, heat the milk over medium-low heat until it reaches about 110°F/45°C. Remove from the heat.

In the bowl of a stand mixer fitted with the dough hook, mix the flour, sugar, yeast, and salt on low speed to combine. Add the warm milk, egg, egg yolk, and butter and mix for 4 minutes. Raise the speed to medium and mix until the dough is smooth, about 2 minutes more.

Transfer the dough to a lightly greased large bowl, cover with plastic wrap, and let rise until visibly puffy, 45 minutes to 1 hour and 15 minutes.

When the dough has risen, divide the dough into 9 equal-sized pieces (about 100 grams each). Working with one piece of dough at a time, gently press and stretch the dough into a rectangle about 4x5 inches (10x13 cm).

In a large skillet, heat 1 tablespoon (15 grams) of olive oil and the butter over medium heat until the butter melts. Add the cabbage and cook, stirring frequently, until it wilts, about 10 minutes.

Add the onion, season the mixture with salt and pepper, and cook until it and the cabbage are very tender, 8 to 10 minutes more. Transfer the mixture to a medium bowl.

Add the remaining 1 tablespoon (15 grams) olive oil to the skillet and heat over medium-high heat. Add the ground beef, and season with the Worcestershire, onion powder, garlic powder, smoked paprika, and salt and pepper. Cook until the beef is fully cooked and well browned, 4 to 5 minutes. Add to the bowl with the cabbage and onions and mix well to combine. Let the mixture cool for 15 minutes.

Fold the shredded cheese into the filling mixture until well combined. Line two baking sheets with parchment paper.

Scoop a heaping ¼ cup (about 70 grams) of the filling into the center of the dough, shaping it roughly into a log. Fold the excess dough over the filling to fully encase it, and pinch the seams well to seal. Roll the dough gently to help flatten the seams, forming a rectangular 'log' of dough.

As you shape them, transfer the runzas to the prepared baking sheets, staggering them into rows. Use the palm of your hand to gently flatten each pastry by pressing gently down.

Cover the shaped pastries with greased plastic wrap or a clean kitchen towel, and let rise for 45 minutes to 1 hour, until the dough is visibly puffy. Toward the end of rise time, heat the oven to 350°F/175°C.

Uncover the pastries, and egg wash the surface and sides evenly. If using, garnish with sesame seeds. Transfer the oven and bake, rotating the baking sheets halfway through baking, until golden brown, 25 to 30 minutes. Cool 5 to 10 minutes before serving warm.