Does it have to be a cake?
Stupidly simple ideas that people love and it looks like you went all out.
Pumpkin or Key Lime dip in a bowl on a platter surronded by store bought vanilla wafers. Both are very good.
Peppermint Bark Cookies;
1 box of old fashioned chocolate wafer cookies
melted white chocolate
crushed candy canes
Dip a corner of a wafer in white chocolate, sprinkle with crushed peppermint. They're delicious, look stunning on a platter, and you do it from start to finish in 15 minutes.
Another huge cheat that looks like you've really outdone yourself:
Ritz crackers
peanut, almond, cashew, or cookie butter
melted chocolate (stir in some crisco or parrafin so it doesn't bloom after dipping if you're not into tempering)
Make sandwiches with the crackers and butter. Dip in chocolate, place on sheets of waxed paper to set.