In 1981 while working for Marriott Hotels I competed in a pastry competition. I took first place with my Blueberry Muffins. It was also the very first thing I showed on morning TV. in 1993 in Live in LA. I still have not found a better blueberry muffin.
Here is the recipe
To make cookies and muffins uniform you need to use a "disher". They look like an ice cream scoop with a spring loaded handle, but it is for food. They are numbered from 100 to 8. 100 being the smallest. The numbers mean how many scoops you get out of a quart of mashed potatoes. Here is the one I recommend. With so many on the market, you need a disher that is made for heavy use.
Disher on Amazon
Enjoy and have a great weekend.