The next day, grease a muffin pan with olive oil. Set aside for now.
Remove the dough from the fridge, and loosen it from the sides of bowl (it may be sticky). Turn upside down onto a lightly floured counter. Pat the dough into a rough rectangle.
Using a sharp knife or bench scraper, divide the dough in half, and then cut six pieces from each half for a total of twelve pieces of dough.
Shape each dough piece into a ball, and place each dough ball inside a muffin tin. The dough does not have to be perfectly round, but it should fit snugly inside the tins.
Allow the dough to rise, covered, for 2-4 hours. The dough will slowly puff up.
Meanwhile, prepare the Rosemary Topping by mixing together the olive oil and rosemary together in a small bowl.
Preheat the oven to 450 F.
Oil your hands and poke deep holes all over the top of the dough. Don’t be shy–you want there to be lots of holes that touch the bottom of the pan!
Drizzle the Rosemary Topping evenly over each of the muffins. You may not use all of the oil.
Place the muffin pan on a baking sheet to catch any dripping oil, and bake for 20-25 minutes, until the tops are golden brown.
Brush the hot focaccia muffins with melted butter and sprinkle with the finishing salt before serving.