Preparing the cookies:
Preheat the oven to 350°F and prepare a baking sheet with parchment paper.
In a large bowl, beat the butter together with the white sugar and brown sugar until the mixture is creamy and well combined.
Add the egg and vanilla extract, and mix well.
In the same bowl, sift together the flour, baking powder, baking soda, and salt. Gradually incorporate these dry ingredients into the wet mixture, mixing until well combined.
Gently fold in the fresh blueberries, being careful not to break them too much.
Preparing the Quick Jam:
In a small bowl, mix the fresh blueberries with the sugar.
Microwave for one minute.
Mash the blueberries with a fork until you have a thick jam. Let cool.
Preparing the Streusel:
In a small bowl, mix the butter, sugar, flour, and a pinch of salt. Mix with a fork or your hands until the mixture is crumbly.
Baking:
Use a #20 scoop to portion the dough and ensure all cookies are the same size. Place the dough portions on the prepared baking sheet, leaving space between each cookie.
Make a small indentation in the center of each cookie dough portion and add a teaspoon of blueberry jam.
Sprinkle the streusel over the cookies.
Bake the cookies for 13-15 minutes or until the edges are lightly golden.
Let cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.
Preparing the Glaze:
In a small bowl, mix the powdered sugar with the lemon juice until smooth.
Drizzle the glaze over the cooled cookies.