In a small bowl, combine the warm milk and brown sugar. Sprinkle the active dry yeast over the top and let it sit for about 5-10 minutes until it becomes frothy.
In a large mixing bowl, whisk together the all-purpose flour, salt, and lemon or orange zest.
In another bowl, mix the slightly beaten eggs and sweetened condensed milk. Once the yeast has activated, add the yeast mixture to the wet ingredients, mixing well to combine.
Gradually add the wet mixture into the dry ingredients, stirring until a dough begins to form.
Transfer the dough to a floured surface and knead for about 8-10 minutes until it becomes smooth and elastic.
Place the kneaded dough in a lightly greased bowl, cover it with a kitchen towel, and let it rise in a warm place for about 1 hour, or until it doubles in size.
Once the dough has risen, punch it down to release the air. Divide the dough into 12 equal pieces, shaping each piece into a ball.
Cover the shaped rolls with a kitchen towel and let them rise for another 30 minutes.
While the rolls are rising, preheat your oven to 350°F (175°C).
Brush the tops of the rolls with the beaten egg, and if desired, sprinkle sesame seeds on top. Bake in the preheated oven for 20-25 minutes or until golden brown.
Once baked, remove the rolls from the oven and let them cool on a wire rack.
