Shading and detail work are the best part of this here picture. The texture of the pumpkin(-shaped thing), of the hair, of the stalk of the pumpkin, of the candles, of the cape and hat and that interesting super-smooth coat of Trixie's. All are quite interesting to behold. In addition to that, you shaped her rather well and brought proper volume to her body with that very same shading. Well done.

Good to see more ponies from you.