As a rule, a CTE will NEVER improve performance. A CTE is essentially a disposable view. There are no additional statistics stored, no indexes, etc. It functions as a shorthand for a subquery. In my opinion they can be EASILY overused (I see a lot of overuse in code in my job).
Check the cupcakes at the minimum baking time. If the recommended baking time is 18-22 minutes, check them at 17 or 18 minutes (just a quick peek, make sure not to let too much heat out of the oven). If the tops are rounded and no long appear wet, they may be done.
Dark pans give your cakes a darker finish when baked. Cupcake Baking Time: It takes about 21 to 26 minutes for regular-sized cupcakes and about 10 minutes for mini-cupcakes to bake fully. Always check to see if cupcakes are done as soon as they reach the minimum baking time.