Mix the dough: Use a cheese grater to grate 8 tablespoons butter into a mixing bowl. Add 2 ½ cups all-purpose flour and use a bench scraper or pastry cutter to cut the butter into the flour. Add ⅓ cup sourdough starter discard, ¾ cup milk, 1 tablespoon honey, and ¾ teaspoon fine sea salt. Mix with a spatula until the ingredients are well incorporated. Cover the bowl and let rest on the counter for 10-12 hours. (DO NOT add the baking soda or baking powder. This will be added right before rolling out the dough)

Preheat oven to 375°F (190°C) and butter a 9" x 13" baking dish. You can also use a 12" cast iron skillet or a baking sheet lined with parchment paper.

Add the leavening agents: Mix 1 teaspoon baking powder and ½ teaspoon baking soda in a small bowl with a fork until there are no visible lumps. Sprinkle the mixture on top of the dough and mix it in with your hands. The dough will become sticky as you mix the ingredients; this is normal.

Roll out the dough: Generously flour your work surface and turn the dough onto it. Flour the top of the dough. Use a rolling pin to roll the dough into a 14" x 14" square.

Add the fillings: Sprinkle 6 oz shredded Swiss cheese over the dough, leaving a border around the edges. Layer 8 oz ham slices over the cheese.

Cut out rolls: Roll the dough into a log shape. Use the bench scraper to cut the dough log into 12 pieces. Arrange the rolls in the baking dish.

Make the poppyseed butter sauce: In a bowl, mix ½ cup unsalted butter, melted, 2 tablespoons Dijon mustard, 2 teaspoons Worcestershire sauce, 1 tablespoon poppy seeds , ½ teaspoon garlic powder, and ½ teaspoon onion powder. Pour the poppyseed butter sauce over the rolls and use a pastry brush to make sure they are evenly coated.

Bake: Bake the rolls for 30 minutes or until the tops are golden brown.