Step 1: In a large bowl or the bowl of a stand mixer, combine the warm milk, active dry yeast, and 1 teaspoon of the granulated sugar. Stir gently and let it sit for 5-10 minutes until foamy, indicating the yeast is active.
Step 2: Add the remaining granulated sugar, sweetened condensed milk, and egg to the yeast mixture. Whisk until well combined.
Step 3: Gradually add 3 ½ cups of the all-purpose flour and the salt to the wet ingredients. Mix on low speed (with a stand mixer and dough hook) or by hand until a shaggy dough forms.
Step 4: Add the softened butter, then increase mixer speed to medium-low (or continue kneading by hand) for 8-10 minutes until the dough is smooth, elastic, and pulls away from the sides of the bowl. Add the remaining ½ cup flour if the dough is too sticky, a tablespoon at a time.
Step 5: Transfer the dough to a lightly oiled bowl, turning once to coat. Cover the bowl with plastic wrap or a clean kitchen towel and let it rise in a warm, draft-free place for 1 to 1.5 hours, or until doubled in size.
Step 6: Gently punch down the risen dough and turn it out onto a lightly floured surface. Divide the dough into 12 equal pieces. Shape each piece into a smooth, round ball.
Step 7: Arrange the shaped rolls in a lightly greased 9x13 inch baking dish, leaving a small space between each. Cover the dish loosely with plastic wrap or a kitchen towel and let them rise again for 30-45 minutes, or until nearly doubled in size.
Step 8: Preheat your oven to 375°F (190°C).
Step 9: Bake the rolls for 20-25 minutes, or until golden brown on top. If the tops are browning too quickly, you can loosely tent them with foil.
Step 10: Once out of the oven, immediately brush the tops of the hot rolls with the 2 tablespoons of melted butter. Serve warm and enjoy!