In a large bowl, combine the warm milk, sugar, and active dry yeast. Let it sit for about 5-7 minutes until it becomes bubbly and frothy.

Add the melted butter, egg, and salt into the yeast mixture. Gently stir to combine, then begin adding flour, one cup at a time, until a soft dough forms.

Turn the dough onto a floured surface and knead for about 5 minutes until smooth and elastic.

Shape the dough into a ball and place it in a greased bowl. Cover with a clean towel and let it rise in a warm area for about an hour, or until doubled in size.

Mix together the filling ingredients: softened butter, brown sugar, and cinnamon in a bowl until well combined.

Once the dough has risen, punch it down gently, roll it out into a rectangle about 1/4 inch thick.

Spread the cinnamon filling evenly over the dough, leaving space around the edges.

Roll the dough tightly from one end to the other, sealing the edges. Slice into 12 equal pieces and place in a greased baking dish.

Cover with a towel and allow to rise for another 30 minutes while preheating your oven to 350°F.

Bake the cinnamon rolls for 20-25 minutes, or until golden brown.

For the icing, whisk together powdered sugar, milk, and vanilla, then drizzle over warm rolls.