1large egg yolk, beaten with 1 Tablespoon water (for egg wash)
In the bowl of a stand mixer, combine the butter, sugar, salt and 1 1/2 cups warm water. Sprinkle the yeast on top. Add the flour and mix with the dough hook attachment on low speed. Once the dough comes together, increase the speed to medium and mix for another 4 to 5 minutes, until the dough is smooth and pulls away from the sides of the bowl. Remove the dough from the bowl, wipe the bowl and then spray with the vegetable oil. Return the dough to the bowl, turning once to cover both sides with the oil. Cover tightly with plastic wrap and let rise in a warm place for approximately 45-50 minutes, or until doubled in size.
Preheat the oven to 450 degrees F and adjust the oven rack to the lower third of the oven. Line a large baking sheet with parchment paper and lightly spray with vegetable oil; set aside. (Alternatively, you can use a silicone liner with no spray.)
Turn the dough out onto a slightly oiled work surface or pastry mat. Divide the dough into 8 equal dough balls. Working with one portion of dough at a time and keeping the rest covered with a clean kitchen towel, roll the dough ball into a 4x8-inch rectangle.
Layer a tablespoon of cheese right down the middle, then 6-8 pepperoni slices. Top with another tablespoon or two of cheese.
Fold down the top (short ends) of the rectangle, then fold up the bottom.
Fold in the wide sides over top each other.
Pinch all seams shut and gently roll to shape into a log. Set on the lined baking sheet and cover lightly with another clean kitchen towel. Repeat with the remaining 7 dough balls.
Once all stromboli's are shaped and placed on the baking sheet, let rest for about 10 minutes, covered with the kitchen towel.
Meanwhile, bring the 10 cups of water to a boil in a large sauce pan or stock pot, then add the baking soda.
Carefully place two logs in the boiling water for 30 to 40 seconds, turning once. Use a large slotted spoon or spatula to remove from the water and return to the pan. Repeat with remaining stromboli logs. Brush the top of each log with the egg wash then sprinkle with kosher salt. Use a sharp knife to score shallow diagonal lines on the top of each log.
Bake in the preheated oven until dark golden brown and the sound of tapping the loaf is hollow (approximately 10 to 15 minutes.) Allow to cool on a wire rack for 3-5 minutes before serving. Serve with your favorite pizza dipping sauce.
If you do not plan to consume the bread the same day, then I would suggest freezing immediately after they hit room temperature. The more fresh they are when you freeze them, the better. Throw them in a freezer bag and freeze up to 1 month. Reheat in the microwave.