Set the butter in a large heatproof bowl. Pour the sugar over it and set it in the microwave for 60 seconds. The butter should be nearly fully melted, whisk the mixture well.
Grind 34g of the freeze dried blueberries (if you have leftover blueberries, immediately seal the bag as they will turn gummy if exposed to air) and immediately pour the powder into the bowl and whisk well. Return to the microwave for 30 seconds. Add the salt and a dash of vanilla and whisk very well, until the mixture turns shiny and cohesive.
Add the egg and whisk well. Add the flour (if using cup measurement, sprinkle the flour into the measuring cup and level it) and baking soda. Switch to a rubber spatula and stir to combine.
Chop the chocolate (if using bar chocolate) and pour into the bowl. Chop the other 22g of blueberries and immediately stir into the mixture. Cover the bowl with plastic wrap and chill in the fridge for 2-4 hours.
Preheat the oven to 350 F. Line two baking sheets with parchment paper (grease the pan first so the parchment stays in place).
Scoop the cookies into 2-2.5 tablespoons of dough per cookie. Bake until the cookies have golden edges, have spread and are matte in the center (they shouldn’t look wet) - about 12-13 minutes, depending on the size of the cookie.