Preheat your oven to 350°F and line a cookie sheet with parchment paper. Set aside.

In a stand mixer fit the paddle attachment, beat the butter and granulated sugar together until light and airy, about 2 minutes.

Use a rubber spatula to scrape down the sides of the bowl and add the egg and vanilla extract. Beat until smooth and fluffy, about 2 minutes.

Add the flour, baking powder, baking soda and salt. Mix on low speed, gradually increasing to high. Mix until no streaks of flour remain. Add the milk and mix until combined. Do not over mix.

Gently fold in the blueberries.

Drop the jam into your dough and fold the dough a few times to distribute the jam. Do not fold it too many times-you want big ribbons of jam!

In a separate bowl, combine all the ingredients for the streusel topping and use a fork to mixture until crumbly and clumping together.

Use a 1.5 ounce cookie scoop to scoop out the dough onto your prepared baking sheet. Top with a heaping spoonful of the streusel topping, really pressing it into the dough.

Bake the cookies for 12 to 15 minutes or until the edges are set, but the centers are still a little doughy. Allow to cool completely before eating!