Place the frozen dinner rolls in a large 10-12-inch lightly buttered cast iron skillet, allowing some space between the rolls. Cover with a tea towel or dish cloth and set aside in a warm place to rise for at least 2 to 2 1/2 hours.
When risen, the rolls should be puffy and soft. Gently brush melted butter onto the rolls. Sprinkle the rolls with rosemary and sea salt.
Bake at 400 degrees for 15 to 18 minutes, until nice and golden brown. Remove from the oven and allow to cool in the pan. Serve warm with a pat of butter.