Preheat a waffle iron to medium-high heat. Lightly brush the top and bottom of the waffle iron with 2 tablespoons melted butter.
To make the cinnamon sugar, combine sugar, brown sugar and cinnamon; set aside.
To make the cream cheese glaze, combine cream cheese, confectioners’ sugar, milk and vanilla in a small bowl until smooth; set aside.
In a large bowl, combine flour, baking powder, pumpkin pie spice and salt; set aside.
In a large glass measuring cup or another bowl, whisk together buttermilk, pumpkin, eggs, brown sugar and remaining 4 tablespoons butter. Pour mixture over dry ingredients and stir using a rubber spatula just until moist.
Pour a scant 1/3 cup of the pumpkin mixture into the waffle iron, close gently and cook until golden brown and crisp, about 4-5 minutes. Working quickly, coat each waffle with cinnamon sugar.
Serve immediately, drizzled with cream cheese glaze.