Preheat oven to 375 degrees F. and prepare a 12-cup muffin tin by lining cups with parchment and greasing the parchment or by inserting paper cupcake cups. (It is possible to make 16 or so muffins by reducing the amount of batter you put into each muffin tin. I did this and the muffin size was perfect.)

In the bowl of your stand mixer, beat butter and sugar together until it is well-mixed. Add the eggs one at a time. Beat the mixture well after the addition of each egg. Add the baking powder, salt and vanilla. Mix well, scraping the bottom of your bowl to be sure that all the ingredients are incorporated into the batter.

Add the flour alternating with the milk. Mix these ingredients together gently--just to combine. Scrape the bottom and sides of the bowl to be sure all the ingredients are mixed together.

Mash 1/2 C. of blueberries. Add these mashed berries to the batter along with the remainder of the whole berries. Mix just to combine.

Using a 1/4 C. measure, scoop portions of the batter into the muffin tins.

Sprinkle 1/2 t. granulated sugar on top of each muffin and bake for about 30 minutes. You want the tops of your muffins to be a light golden brown. Your muffins are done when you can stick a toothpick into the center of a muffin comes out clean. (I gave my muffins a few extra minutes of baking to get just the golden brown color that I wanted. Baking times will vary from oven to oven.)

Remove muffins from the oven. Gently (the muffins will be tender at this point) loosen the edges of the muffins from the edges of the pan, or, if you are using cupcake cups, loosen the cups within the muffin tins. Let the muffins sit for about 5 minutes and them remove them from the muffin pan. Cool on a rack.

These muffins were delicious but very tender on the first day. They were perfect on the second day.