- Preheat oven to 350 degrees. 
- Line 10" round baking pan with parchment on the bottom. 
- Spray parchment lined pan with cooking spray on bottom & sides. Set aside. 
- In microwave safe bowl- place sweet potato in with enough water to cover bottom. 
- Pierce sweet potato several times- microwave approx 10 minutes. Turn over- microwave another 5-10 minutes until soft like a baked potato. Set aside. 
- Melt chocolate in microwave safe bowl - about 20 seconds. Set aside. 
- In large bowl whisk together flour, baking powder, salt. Set aside. 
- In small bowl, remove skin from sweet potato- mash with fork until no more lumps remain. 
- Use electric mixer, beat butter & brown sugar until fluffy. 
- Beat in eggs one at a time. 
- Reduce mixer to low- mix in mashed sweet potato & then melted chocolate. 
- Add flour & turn on low- pouring in milk as it mixes the flour into mixture. 
- Spread batter into your prepared pan. 
- Bake 35-48 minutes- or until toothpick test is clean. 
- Cool in pan 15 minutes. 
- Flip onto wire rack to cool completely. 
- Flip back to right side onto serving plate. 
- Sprinkle powdered sugar or add icing of choice to taste.