01 -
Combine the flour, brown sugar, cold cubed butter, cinnamon, and salt in a bowl. Use a fork or pastry cutter to cut the butter into the dry ingredients until pea-sized crumbs form. Refrigerate while making the cookie dough.
02 -
In a large bowl, beat the softened butter with the brown sugar and granulated sugar until light and fluffy, about 2-3 minutes. Beat in the egg and vanilla.
03 -
Whisk together the flour, baking powder, and salt in a separate bowl. Gradually mix the dry ingredients into the wet ingredients until just combined. Avoid overmixing.
04 -
Gently fold in the fresh blueberries, being careful not to break them.
05 -
Portion rounds of dough and place them spaced apart on a parchment-lined baking sheet. Dollop blueberry jam on top of each dough round using a spoon or piping bag, then swirl it slightly with a knife or toothpick.
06 -
Remove the streusel from the fridge and generously top each dough round with streusel crumbs. Gently press it into the dough.
07 -
Bake at 375°F (190°C) for 12-15 minutes, until lightly golden but still soft in the middles.
08 -
Allow the cookies to cool completely before enjoying. These are excellent served slightly warm with a glass of cold milk.