Activate the Yeast: In a small bowl, mix the warm milk, granulated sugar, and yeast. Let it sit for 5-10 minutes until frothy.
Mix Dough Ingredients: In a large bowl, combine the yeast mixture, eggs, melted butter, flour, and salt. Mix until a soft dough forms.
Knead the Dough: Turn the dough onto a floured surface and knead for about 8-10 minutes, or until smooth and elastic. Alternatively, use a stand mixer with a dough hook for 5-6 minutes.
Let It Rise: Place the dough in a greased bowl, cover, and let it rise in a warm place for 1 hour, or until doubled in size.
Prepare the Filling:
Make the Filling: In a small bowl, mix the softened butter, granulated sugar, orange zest, and cinnamon (if using).
Assemble the Rolls:
Roll Out Dough: Roll the dough into a 12x18-inch rectangle on a lightly floured surface.
Spread Filling: Spread the orange filling evenly over the dough.
Roll and Cut: Roll the dough tightly into a log, starting from the long edge. Cut into 12 equal pieces.
Arrange and Rise: Place the rolls in a greased 9x13-inch baking dish. Cover and let rise for 20-30 minutes.
Bake:
Bake Rolls: Preheat the oven to 350°F (175°C). Bake the rolls for 25-30 minutes, or until golden brown.
Prepare the Glaze:
Make the Glaze: In a small bowl, whisk together the powdered sugar, orange juice, orange zest, and vanilla extract until smooth.
Finish and Serve:
Glaze the Rolls: Spread the orange glaze over the warm rolls.