1. Combine the active sourdough starter, warm water, and melted butter in a mixing bowl and stir until mostly dissolved.

2. Add flour and salt, then mix until a sticky dough forms and let rest for 30 minutes (autolyse).

3. Knead by hand or in a stand mixer for 8–10 minutes until smooth and elastic.

4. Cover and bulk ferment at room temperature for 4–6 hours until doubled in size.

5. On a floured surface, roll dough into a ½-inch thick rectangle.

6. Brush the surface with garlic butter, then sprinkle evenly with shredded mozzarella, grated cheddar, and chopped herbs.

7. Roll dough into a log from the short side and cut into 2-inch sections.

8. Arrange sections cut side up in a greased loaf pan or cast-iron skillet and proof for 45–60 minutes.

9. Preheat oven to 375°F (190°C) and brush the top with additional melted butter.

10. Bake for 30–35 minutes until the top is golden and cheese is bubbling.

11. Remove from oven, brush with reserved garlic butter, and sprinkle with extra cheese and herbs.

12. Let rest for 5–10 minutes, then serve warm by pulling apart each cheesy layer.

13. Wrap leftovers in foil and store at room temperature for up to 2 days, reheating at 300°F (150°C) for 10–12 minutes or microwaving covered with a damp paper towel.

14. To freeze, cool completely, wrap tightly in foil and a freezer bag, and reheat from frozen at 325°F (165°C) for 20–25 minutes.