In a slow cooker, combine the whole milk, heavy cream, pumpkin puree, granulated sugar, maple syrup, vanilla extract, and pumpkin pie spice. Stir everything together until well mixed.

Set the slow cooker to low heat and cook for about 2 hours, stirring occasionally. The mixture should be heated through and the flavors will meld together nicely.

Once the mixture is hot and well-combined, add the strong brewed coffee or espresso to the slow cooker. Stir it in thoroughly.

Taste the latte and adjust the sweetness or pumpkin spice according to your preference. You can add more sugar or pumpkin pie spice if needed.

Now, it's ready to serve! Pour the Pumpkin Spice Latte into mugs and top each with whipped cream (if desired) and a sprinkle of ground cinnamon or nutmeg.