Make the dough. In a large mixing bowl, mix flour, sugar, yeast, salt, cinnamon, and nutmeg. Alternatively, you can use a stand mixer fitted with the dough hook attachment.

Add the butter in a medium microwave-safe bowl and melt in the microwave in 15-second intervals until fully melted. Add milk and sour cream, and heat again for 15 seconds more. Whisk to combine.

To the flour mixture, add milk mixture, egg, and vanilla. Start mixing it on low speed until it comes together, then increase speed to medium-low and continue kneading until it becomes springy and tacky to the touch. It will take about 8 to 10 minutes.

Place the dough in a lightly oiled large bowl, cover it with cling wrap, then let it rise in a warm place until it doubles in size. It will take about an hour.

Make the filling. In a medium bowl, mix butter and dulce de leche. In a separate small bowl, stir brown sugar and cinnamon.

Take a 9-inch baking pan and lightly grease it with butter.

Transfer the risen dough onto a well-floured surface. Flatten it into a roughly 12 x 18-inch rectangle.

Add the butter mixture onto the flattened dough and spread in a thin and even layer, leaving a ½-inch space on one long side. Sprinkle cinnamon sugar on top.

Starting on the unbuttered end, roll up the dough into a tight long log, then cut it into nine 2-inch wide pieces using a sharp serrated knife or unflavored dental floss.

Place the rolls cut side-down on the prepared baking dish, spacing them evenly. Loosely cover and place in a warm area. Let the rolls rise until they almost double in size. It will take about 30 minutes. Preheat your oven to 350F while waiting.

Uncover the rolls and bake for 30 minutes. Once done, place on a wire rack to cool.

Remove the rolls from the oven and spread a third of the glaze. Let them cool for 5 minutes, before spreading the remaining glaze.