Combine milk, yeast and sugar in a large bowl; let stand for 10 minutes. Stir in eggs and margarine with a wooden spoon. Mix salt into flour; add flour to wet mixture one cup at a time until dough forms. Knead until smooth; place dough in a large bowl sprayed with non-stick vegetable spray.Cover; let rest until double in size. Generously spray a surface with non-stick vegetable spray; roll out dough into a 21-inch by 16-inch rectangle. Spread with butter; combine brown sugar and cinnamon and sprinkle over top. Roll up dough and slice into 12 rolls; arrange in a lightly greased 13"x9" baking pan. Cover and let rise until nearly double in size, about 30 minutes. Bake at 400 degrees until golden, about 15 minutes. Spread warm rolls with frosting; serve warm.