Use a 2-quart slow cooker for best results. Pour the brewed coffee into your slow cooker and whisk in the milk, pumpkin, sugar, vanilla, and pumpkin pie spice. Cover and cook on high for 2 hours, or until fully hot. Whisk again, then ladle into serving mugs with a dollop of whipped cream.
Notes
You can make your own pumpkin pie spice by combining 1/2 teaspoon ground cloves, 1/2 teaspoon ground nutmeg, and a scant pinch of ground ginger.