In a small bowl, mix warm water and 1 tsp sugar.
Add active dry yeast and wait for it to foam (about 10 minutes).
In a big bowl, mix 1 cup milk, melted butter, sugar, salt, and yeast mix.
Gradually add flour until the dough isn't sticky.
Knead on a floured surface for 5 minutes. Put in an oiled bowl, cover, and let rise for 1 hour.
Mix soft butter, brown sugar, and cinnamon until smooth.
Roll dough into an 18x12-inch rectangle.
Spread cinnamon mix evenly, roll into a log, and cut into 12 pieces.
Place on a greased sheet, cover, and rise for 30 minutes. Heat oven to 375°F (190°C).
Bake for 25 minutes or until golden. Cool before putting on frosting.
Mix powdered sugar, vanilla extract, and 1 tbsp milk for frosting.
If it's too thick, add more milk to make it thinner. Put it on the cooled rolls.