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.
Photo Credit Dyana Rzentkowski/Demand Media. Place the mini cupcake pan in the preheated oven and bake the cupcakes for 10 minutes. Open your oven and, using potholders, rotate the pan 180 degrees. Bake the cupcakes for about 5 minutes longer, or until the tops are firm to the touch.