1. In a medium saucepan, heat 3½ cups of milk with cinnamon over medium heat until it starts to steam. Do not boil.
2. In a separate bowl, whisk together MASECA® corn masa flour with the remaining ½ cup of milk until smooth. Whisk in the pumpkin purée, brown sugar, cloves, nutmeg, ginger, and a pinch of salt into the steaming milk. Continue stirring until the sugar dissolves.
3. Slowly pour the MASECA® mixture into the saucepan while whisking constantly to prevent lumps. Keep stirring as the atole thickens, about 8–10 minutes. The texture should be creamy and slightly thick; enough to coat the back of a spoon.
4. Stir in the vanilla extract and remove from heat.
5. Pour into mugs and top with a dollop of whipped cream or a light dusting of cinnamon. Serve hot.