Ah hah! I predicted a cake-based Papa game would emerge eventually! :D
As always, nice art and animation. I like the actual time passage and holiday additions in this one; it really helps to lessen the monotony. I also found that the overall rhythm of the gameplay was some of the smoothest and most enjoyable I've found in the Papa series. I often find that's the case when you have even cooking times for the food, as opposed to games like Hotdoggeria or Taco Mia where you're constantly juggling around your customer queue in order to appease the different meat cooking times.
It's not without its flaws though. Out of all the Papa games, I think Cupcakeria has the single-most PICKY building score calculator. I don't know why, but it feels like I need microscopic precision just to get 98%. I've never had this much difficulty getting a perfect score on the orders, and it's a bit frustrating (on the plus side, I guess it WILL provide me a long-term challenge as I progress).
Also, while some of the upgrades are incredibly useful (ALL HAIL THE FROSTING COPIER), I honestly found no point whatsoever to the fill markers. I couldn't even SEE them, for one, plus it's pretty easy to pour perfect once you memorize the stopping point on the meter (just watch for the center of the vanilla-flavor batter button).
Overall though, easily one of my favorites. Great job, Flipline :)