In a large bowl, whisk together all-purpose flour, instant rapid-rise yeast, sugar, and salt. Warm the lukewarm milk and melted butter to about 100–115°F, then add this mixture along with a beaten egg to the dry ingredients. Stir until a soft dough forms, then knead on a floured surface for 3-5 minutes until smooth and elastic. Place the dough in an oiled bowl, cover, and let it rise in a warm place for 30 minutes or until doubled.

Once the dough has risen, punch it down gently and transfer it to a lightly floured surface. Roll the dough into a 19 × 13-inch rectangle, ensuring an even thickness. Spread melted butter over the surface, then sprinkle an even layer of brown sugar, ground cinnamon, and optional nuts. Starting from the long end, roll the dough tightly into a log shape and slice it into even rolls, approximately 1 to 1.5 inches thick.

Preheat your oven to 350°F (175°C) while the rolls rest. Arrange the rolls in a greased baking pan, spacing them slightly apart. Cover the pan and let the rolls rise for an additional 20 minutes until puffy. Bake the rolls for 25-30 minutes, or until they are golden brown and the edges are set. Remove them from the oven and allow them to cool slightly in the pan.

While the cinnamon rolls cool, prepare the cream cheese frosting. In a mixing bowl, beat together softened cream cheese, melted butter, milk, and pure vanilla extract until smooth and creamy. Adjust the consistency by adding more milk if needed; it should be spreadable yet thick.

Once the cinnamon rolls have cooled for about 10 minutes, generously spread the cream cheese frosting over the warm rolls. The heat will melt the frosting slightly, allowing it to seep into the rolls. Cut and serve your delectable homemade cinnamon rolls while they are still warm.