While the dough rises, prep your filling. Peel and dice your apples into small pieces (about 1/4 inch) – larger chunks can tear the dough when rolling. Mix the brown sugar, cinnamon, and nutmeg in a small bowl.
Once doubled, punch down the dough and turn it onto a lightly floured surface. Roll it into a large rectangle, roughly 18×12 inches. The dough should be about 1/4 inch thick.
Spread the softened butter all over the dough, leaving about a 1/2 inch border at the edges. Sprinkle the cinnamon-sugar mixture evenly over the butter, then distribute the diced apples.
Starting from the long edge, roll the dough up tightly – like rolling a sleeping bag. Keep it snug but don’t pull so hard that you stretch the dough. Pinch the seam to seal it.
Cut the log into 12 equal pieces using a sharp knife or unflavored dental floss (my preferred method – just slide it under, cross the ends, and pull). Place the rolls in a greased 9×13 inch baking pan, leaving some space between each one.
Cover and let rise again until puffy, about 30-45 minutes. Meanwhile, preheat your oven to 350°F.
Bake for 25-30 minutes, or until the tops are golden brown and a thermometer inserted into the center roll reads 190°F. If they’re browning too quickly, tent with foil.