Generously butter 2 disposable foil trays - round ones are best.
Whisk together warm milk, melted butter and granulated sugar. Mixture should be just warm. (98-104f or 37-43c). Sprinkle yeast over warm milk and leave for 1 minute.
Add 500g flour to the milk mixture and stir with spoon until combined, cover with clingfilm and leave rest in a warm place for 1 hour.
Remove clingfilm and add 100g of flour, baking powder and salt. Stir well and turn onto well floured surface. Knead the dough lightly adding more flour as necessary. The dough is ready when it's smooth and doesn't stick to the surface.
Using a floured rolling pin, roll the dough out into a large rectangle approx 1cm in thickness. Trim the edges so that it looks even. DON'T throw out the trimmings. These fellas can be the kids' mini cinnamon rolls!
First, spread a layer of the homemade dulce onto the pastry. Then, spread the softened butter over the dough using the back of a spoon. Sprinkle the brown sugar & cinnamon onto the buttered dough, pressing them gently onto the dough.
Roll up the dough to form a log (like an old school swiss roll) and pinch the seam closed. Cut the dough in half and then cut each half into equal sized pieces. Approx 7 per half.
Place cinnamon rolls in buttered foil containers. Starting with one in the center and working the other around it.
Cover with clingfilm and leave rest for 30mins. Meanwhile preheat the oven to 350f/180c. Remove clingwrap and place in oven and bake for 25-30 mins until golden brown.