In a mixing bowl, add in the flour and butter. Cut the butter into your flour using your fingers or a pastry cutter. The butter should be about pea-sized.
Sprinkle in the salt and give it a mix.
Add in the milk and sourdough discard and mix the dough together with a wooden spoon. The dough should come together pretty easily. Once it can be formed into ball, put the dough in glass container and cover with the lid. Let it sit in the fridge for 12-24 hours to ferment.
Preheat the oven to 400 degrees.
Roll the dough out into a rectangle. Fold the dough onto itself in thirds, like you a letter. Roll the dough out again and repeat this process two more times. The third time, roll the dough out into a rectangle until it is about 1/4 inch thick. The rectangle should about 16 inches long and 10 inches wide.
Cut the dough in half lengthwise. Cut each long piece into four equal squares.
Top each square with a piece of cheese, leaving a thin boarder for sealing.
Place the hotdog on top of the cheese and roll up the hotdog with the cheese and dough. Gently seal the edge with your fingers. Place them on a baking sheet lined with parchment, seam side down.
In a small dish, whisk an egg with a splash of water to make an egg wash. Brush the egg wash on the top and sides of the dough.
Bake for 20 minutes or until the dough is a deep golden brown.
These are best dipped in ketchup. They can be stored in the freezer for up to 3 months and reheated in the oven or microwave.
