Preheat the oven to 375 degrees F., rack in the middle position.
Rinse and thoroughly dry the blackberries. You can do this in a strainer and let them dry while you mix up the cookie dough. (If you're using frozen blackberries, you don't have to rinse them-just put them in a strainer and let them thaw.)
Prepare your baking sheets by lining them with parchment paper and then spraying the paper with Pam or another nonstick cooking spray.
Place the white sugar and the softened salted butter in the bowl of an electric mixer.
Beat them together until they are light and fluffy.
Add the baking powder, salt, and grated lemon zest. Mix them in thoroughly.
Add the egg and mix until it is completely incorporated.
Add one cup of flour to your bowl. Mix it in.
Add the milk to your bowl. Mix that in.
Add the rest of the flour and mix until all the ingredients except the blackberries are combined.
Turn off the mixer, take out the bowl, and set it on the counter.
Pat the strained blackberries with a paper towel until they are thoroughly dry.
Add them to the dough in the bowl and gently fold them in with a rubber spatula. The goal here is to keep as many whole, uncrushed berries as possible. Some will crush and juice. It's inevitable. Don't despair because that is what will give your cookies streaks of lovely purple color.
Drop the cookies by teaspoonful onto the parchment covered cookie sheet, 12 cookies to a standard-size sheet. (Lisa and I use a 2-teaspoon cookie scoop to make these down at The Cookie Jar.)
Bake the Fresh Blackberry Cookies at 375 degrees F., for 12 to 15 minutes or until they are a light, golden brown color.
Yield: 2 to 3 dozen, depending on cookie size.