Make the Dough
In a large mixing bowl, combine flour, sugar, yeast, and salt. Add warm milk, melted butter, and egg. Mix until a dough forms.
Knead the dough on a floured surface for about 8–10 minutes until smooth and elastic. Place in a greased bowl, cover with a clean towel, and let it rise in a warm place for 1 hour or until doubled in size.
Prepare the Filling
In a small bowl, mix brown sugar and cinnamon. Set aside.
Roll and Fill the Dough
Roll the dough into a 12x18-inch rectangle. Spread softened butter evenly over the dough. Sprinkle the cinnamon-sugar mixture on top, covering the surface.
Roll the dough tightly into a log, starting from the long side. Slice into 12 equal rolls.
Prepare the Caramel Sauce
In a small saucepan, melt butter over medium heat. Stir in brown sugar, heavy cream, vanilla, and salt. Cook until smooth and slightly thickened, about 2–3 minutes. Pour the caramel sauce into a greased 9x13-inch baking dish.
Assemble and Bake
Place the rolls cut-side up into the baking dish on top of the caramel sauce. Cover and let rise for 30 minutes.
Preheat the oven to 350°F (175°C). Bake the rolls for 25–30 minutes or until golden brown.
Serve
Let the rolls cool slightly before flipping the baking dish onto a large serving platter, allowing the caramel to coat the rolls. Serve warm.