Preheat the oven to 450 degrees F. Line a baking sheet with parchment paper.
Place the sweet potatoes on one of the prepared baking sheets. Bake until the sweet potatoes are soft to a light squeeze (with a mitt or towel), 45 minutes to an hour.
Meanwhile, toast the pepitas in a dry skillet, stirring occasionally, until fragrant, 2 to 3 minutes. Remove from the heat and set aside.
Add the brown sugar and spices to a medium skillet over medium-high heat and cook until the skillet is hot. Add 1 tablespoon water to the skillet and stir until the sugar is melted. Stir in the pepitas until they are completely coated, then spread the mixture on the other lined baking sheet. Let cool completely.
Let the sweet potatoes cool slightly. Slice them in half, then lightly mash the flesh in the skin with a fork. Transfer the sweet potatoes to a serving tray. Dollop each with about 1/4 cup sour cream, then sprinkle each with the pepitas and mint. Serve immediately.