Prepare the coffee base by combining coffee grounds and 2 cups coconut water. Let sit overnight (or up to 4 days in the fridge), then strain.

Make the pumpkin spice mixture by combining pumpkin puree, pumpkin pie spice, black pepper, and maple syrup in a small saucepan. Cook until hot and fragrant.

Combine and heat the latte by slowly stirring in the coconut milk, remaining 1/2 cup coconut water, and vanilla extract into the pumpkin mixture. Bring to a low simmer, stirring often.

Froth the milk mixture by whisking vigorously until frothy once steaming hot.

Assemble the latte by pouring coffee into a mug and adding the frothed milk mixture. Top with whipped cream and cinnamon if desired.