This Event "Sweet Treat Showdown 4 - Treatsylvania Haunt Event" starts on the 15 Oct and is available for 15 days.
Sweet Treat Challenge
You can start this challenge by clicking the Activities tab of this event or just visit the Parkside and tapping the icon of the baking station.
How to win this challenges
Your Sims will have a match with an opponent professional chef to bake over several rounds by creating pastries and desserts. Each round if your sims win, those rewards will be added to the Prize Basket. Your Sims can choose to forfeit (collect the content they have in their Prize Basket and leave) or they can decide to continue to the next round.