Combine ingredients: Combine flour, sugar, yeast and salt in the bowl of a stand mixer fitted with the dough hook attachment. Combine melted butter and milk in a separate measuring jug (make sure the temperature is not over 105°F!! - it will kill the yeast and your dough will be tough). Pour into the bowl with the flour mix.
Knead dough: Knead the dough in the stand mixer on medium-low speed until a smooth ball forms, about 5-10 minutes. Add up to 4-6 more tablespoons milk, one at a time, if your dough isn't smooth yet (this can happen depending on the fat content of your butter, your exact flour and the humidity where you live).
First rise: Shape the dough into a tight ball on the counter, then place back in the bowl and cover with a clean tea towel. Let stand at room temperature until doubled in size, about 45mins - 1 hour.
Fill and cut the rolls:
Prepare filling: In a medium bowl, combine all ingredients for the filling well.
Roll out the dough: Cut dough in half and roll each half on a baking mat or between two sheets of baking parchment into a rectangle of roughly 15 x 12 inches.
Add filling and roll up: Spread half of the prepared cinnamon-sugar-butter filling over each dough rectangle. Starting on the SHORT side, roll each up into a log.
Cut the rolls: Using a piece of unscented dental floss or sewing string, cut each log into 6 rolls (check the post for video instructions and step photos!).
Finish and Bake:
Final rise: Place the rolls in a medium-large casserole dish (about 9x13 inches). There should be some space between the rolls so they can rise and expand. Cover with the dish towel and rise for about 20 minutes, or until big and puffy.
Bake: Preheat your oven to 375°F. Bake the rolls for around 12-15 minutes, or until baked through and just starting to turn golden on the top. Do not overbake! Frost with your favorite frosting while warm.
Different room temperatures, altitudes and yeast types will affect how fast the dough rises.