In a bowl, dissolve yeast and sugar in warm milk and set aside in a warm place to activate the yeast. Add 2 cups flour until well combined. Add eggs, butter, and salt.
Knead at low speed for 4 minutes. Knead at medium speed for 5 minutes until the dough comes off from the bottom and sides of the bowl. Place on a floured surface, cover with plastic, and allow to rest for 1 hour.
Make a long rope and rest for 30 minutes.
Cut the dough into portioned rolls. Roll out dough until about 4 inches long and 2 inches wide.
In a bowl, combine all ingredients and mix well. Season to taste and chill.
Spread chicken filling in the center of the rolled-out dough. Carefully wrap dough over filling, pinching, and sealing seams of the roll. Rest for another 20 minutes.
In a bowl, combine ground beef, onions, and garlic. Season with salt and pepper and set aside.
Spread beef mixture in the center of the rolled-out dough, place a stick of mozzarella cheese in the middle, and form the meat over the cheese so that the meat envelops the cheese completely. Pinch and seal seams of the roll. Rest for another 20 minutes.
In a pan over medium heat, saute onions, garlic, and potatoes in oil for a few minutes, until potatoes are crispy and everything is fragrant.
Mix in corned beef and season as necessary. Cool.
Spread corned beef filling in the center of the rolled-out dough. Carefully wrap dough over filling, pinching, and sealing seams of the roll. Rest for another 20 minutes.
Spread tomato sauce in the center of the rolled-out dough.
Layer pepperoni and sprinkle grated cheese.
Carefully wrap dough over filling, pinching, and sealing seams of the roll. Rest for another 20 minutes.
Combine butter and egg yolks to make an egg wash. Brush over breadsticks.
Bake at 190˚C for 15-20 minutes.