Prepare the Dough: In a bowl, dissolve yeast and sugar in warm water. Let sit for 5 minutes until frothy. Add flour and salt; knead until smooth.
Shape the Pretzels: Divide dough into equal portions. Roll each portion into ropes and twist into pretzel shapes.
Boil in Baking Soda Solution: Preheat oven to 425°F. Bring water mixed with baking soda to a boil; boil each pretzel for about 30 seconds.
Bake Until Golden: Place pretzels on a greased baking sheet, brush with melted butter, and sprinkle with coarse salt if desired. Bake for 12-15 minutes until golden brown.
Create Icing: Whisk together powdered sugar, milk, and cinnamon until smooth.
Drizzle & Serve: Drizzle icing over warm pretzels and enjoy!