Activate the Yeast: In a small bowl or your stand mixer bowl, combine the warm milk, sugar, and yeast. Stir gently and let it sit for about 5–10 minutes until a foamy "cap" forms on top.
Mix the Dough: Add the melted butter, eggs, and salt to the yeast mixture. Using a dough hook or a sturdy spatula, gradually incorporate the flour until a soft, slightly tacky dough forms.
The First Rise: Knead the dough for about 5–7 minutes until smooth and elastic. Place it in a lightly greased bowl, cover with a warm damp cloth, and let it rise in a draft-free spot for 1 hour or until doubled in size.
Roll and Shape: Punch the dough down to release air. On a floured surface, roll the dough into a large 12x18 inch rectangle.
Add the Flavor: Spread the softened butter over the entire surface of the dough. In a small bowl, mix the brown sugar and cinnamon, then sprinkle it evenly over the butter.
The Roll-Up: Starting from the long edge, roll the dough tightly into a log. Using unflavored dental floss or a sharp serrated knife, slice the log into 12 even rolls.
The Second Rise: Place the rolls into a greased 9x13-inch baking dish. Cover and let them rise for another 30 minutes until they look puffy and are touching each other.
Bake to Perfection: Preheat your oven to 350°F. Bake for 22–25 minutes until the tops are a light golden brown.
Glaze and Serve: While the rolls bake, whisk the powdered sugar, milk, and vanilla until smooth. Pour the glaze over the rolls while they are still warm so it melts down into the spirals.
