In a large bowl, mix together sweet potato, flour, baking powder, salt, pepper, garlic powder, eggs, and milk. 

Heat ¼-inch oil in a large skillet over medium heat.  

Line a sheet pan with two layers of paper towels.  

Working in batches, drop ¼ cup batter into oil, and flatten slightly into circles.  Fry until nicely browned, about 4 to 5 minutes per side. Remove from pan, and drain on the prepared pan, and continue with remaining batter.

Preheat broiler.

Remove paper towels from under the latkes. Place a slice of cheese on each latke and broil until cheese is slightly melted and bubbly at the edges, about for 2 minutes.  

Place two latkes on each appetizer plate and top with a few leaves of arugula.