Preheat the oven to 350°F. Line two baking sheets with parchment paper.
In a mixing bowl, combine the protein powder, flour, cinnamon, baking soda, and salt.
In another large mixing bowl, combine the sweetpotato puree, sugar, oil, egg, and vanilla. Whisk until well combined.
Add the dry ingredients to the wet ingredients. Stir until just combined.
Portion the batter onto the parchment-lined baking sheets in heaping spoonfuls; about 1 ½ to 2 tablespoons of batter each to make 20 cakes. Bake at 350°F for 10-13 minutes, until the cakes are cooked through. Let cool on the pan.
As the cakes are cooling, prepare the frosting. Combine the Neufchatel cream cheese, yogurt, protein powder, and powdered sugar in the bowl of a stand mixer (or a mixing bowl if using a hand mixer). Use the whisk attachment of the mixer to beat