In the bowl of a stand mixer with the paddle attachment, cream the butter and sugars until fully mixed and fluffy. Add in the egg, beating until combined, then repeat with the vanilla extract.
In a separate bowl, mix together the flour, baking soda, and salt, then add the dry mixture into the wet mixture and beat until just combined.
Gently fold in the blueberries until evenly dispersed through the cookie dough.
Use a cookie scoop to evenly form 12-14 balls of dough. Chill the dough balls in the fridge for at least 2 hours or covered overnight.
Preheat the oven to 350ºF and prepare a baking sheet with parchment paper.
In a small bowl, mix the butter, flour, brown sugar, and cinnamon by hand until the mixture resembles wet sand and is slightly crumbly.
Arrange the cookies at least 3 inches apart on the baking sheet, then gently press a small handful of streusel onto the tops of each dough ball. Save any extra streusel.
Bake cookies for 10 minutes, then remove from oven and add any extra streusel evenly to the tops of the cookies. Return to the oven and bake cookies for another 5-8 minutes, until the edges have become golden.
Use a round cookie cutter or a large cup to scoot the cookies into even circles, then let them rest at room temperature for at least 5 minutes to finish baking before serving.