Combine milk and butter in a measuring cup, microwave on high until the butter melts. Pour into the bowl of a stand mixer with the paddle attachment on. Add 1 cup of the flour then add the sugar, egg, yeast and salt. Beat on low untill well combined (about 3 minutes). Add the remaining 2 ½ cups of flour and beat untill the mixture forms a dough and pulls away from the sides. Remove from the mixer and kneed untill the dough takes on an elastic texture (about 8 minutes). If the dough is sticky add a bit of flour. Form the dough into a ball and and place in a bowl that has been coated lightly in cooking spray. Turn it over to coat then cover the bowl with plastic wrap and a towel. Let the dough rise for about two hours in a warm area. It should double in volume.
Punch down the dough and transfer to a floured surface. Roll out the dough into a 15 x 11 inch rectangle. Cover the surface in the soft butter and sprinkle the brown sugar and cinnamon mixture over the surface. Begin rolling up the dough, starting on one of the long sides. Once rolled, cut crosswise into 18 even pieces and distribute them evenly amongst two greased 9x9 inch baking pans with the spiral facing upward. Cover the baking pans with plastic wrap and a towel and alow to rise a second time for about 40 to 45 minutes, or until the buns have doubled in size.
Heat oven to 375 degrees and bake the rolls for about 20 minutes, or until the tops are golden. Remove from oven and pan to cool before adding topping.