The Best Blueberry Muffins

No really. These are the best.

Soooo, last summer, we went to a local blueberry field. Many times. Did you know blueberries freeze really easily? They do. And now that summer approaches again, we are going through our freezer, using the last of berries frozen so many months ago. I made these muffins awhile ago and don't remember where I got the recipe, tweaked only slightly. I made them again today. A and I agreed: they are the best. Moist on the inside, with a slightly sweet crispness on the outside. This recipe is a keeper. If you know where the basics come from, do let me know. So I can give due credit.
Meanwhile, from my handwritten notes:

Ingredients: 
0.75 cup of butter
1 cup of sugar
1 egg
0.75 cup of milk
1.75 cups of flour
2.5 teaspoons of baking powder
0.5 teaspoon of salt
1-2 cups of blueberries

Directions:
1. Cream butter and sugar.
2. Add milk and egg. Mix until smooth.
3. Sift together: flour, baking powder, and salt. (Reserve about 1 tablespoon of flour). Add the sifted stuff to the the creamed mixture.
4. In a separate bowl, toss the blueberries with the tablespoon of flour. I learned today that it's totally fine if the berries are still frozen.
5. Next, fold the blueberries into the batter.
6. Pour into muffin tin and bake at 400 degrees F for 20 minutes.

This would make 12 very large muffins. Or, 12 normal muffins and 2 mini-muffiny cakes, if you were to use a couple of greased ramekins for the remaining batter. (For example.)