Add Masarica to large, heavy saucepot. Using whisk, slowly add 4 cups water, whisking constantly until smooth and combined. Place saucepot over medium-high heat; bring Masarica mixture to boil.
Add milk, sugar cane, chocolate and cinnamon to pot. Bring milk mixture to boil, whisking constantly, until chocolate is melted and sugar cane is dissolved, 5-7 minutes more.
Remove pot from heat. Divide champurrado evenly among serving mugs.