Make the dough: In a large bowl, mix flour, sugar, baking powder, and salt. Cut in softened butter until the mixture resembles coarse crumbs. In a separate bowl, whisk together egg and milk, then gradually add to the dry ingredients until a soft dough forms.
Roll out the dough: On a lightly floured surface, roll the dough into a large rectangle about 1/4 inch thick.
Add the filling: Spread softened butter evenly over the dough, then sprinkle with the cinnamon and brown sugar mixture.
Roll it up: Starting from one long edge, roll the dough into a log.
Slice the rolls: Cut the log into 12 equal pieces using a sharp knife.
Prepare to bake: Place the rolls in a greased baking dish, leaving a little space between each. Cover with a clean kitchen towel and let rise in a warm spot for about 30 minutes. Preheat oven to 375°F (190°C).
Bake: Bake the rolls for 25–30 minutes, or until golden brown.
Serve: Let the rolls cool slightly, then drizzle with icing if desired. Enjoy warm!
