Preheat the oven to 425 F. Place a large sheet pan with parchment paper in the oven while it preheats.

Add the sweet potatoes to a mixing bowl, then add 2 tbsp olive oil and toss. Add the spices and starch and toss again. Place them spread out on the sheet pan and roast for 20-23 minutes, flipping halfway. They should easily pierce with a fork or toothpick.

Remove them from the oven, reduce the heat to 375, then use a small piece of parchment paper to cover each sweet potato and use a flat-bottomed glass to mash the potatoes. Brush the tops with the remaining oil, then add 1/2 the Parmesan and roast for 25 minutes, then flip and add the remaining Parmesan to the other side and roast another 25 minutes. Remove them from the oven and allow them to cool slightly—they crisp up as they cool.

Make the crema. Add all ingredients to a food processor or blender and blend until smooth.

Serve with the dip.