Preheat your oven to 350°F (175°C). This ensures that your cookies bake evenly.
In a large mixing bowl, use an electric mixer to cream together the softened butter, brown sugar, and granulated sugar until the mixture is light and fluffy. This should take about 2-3 minutes.
Add the egg and vanilla extract to the butter and sugar mixture. Beat until well combined.
In a separate bowl, whisk together the flour, baking soda, salt, ground cinnamon, and quick oats until evenly mixed.
Gradually add the dry mixture to the wet mixture, stirring until just combined. Be careful not to overmix, as this can lead to tough cookies.
Gently fold in the fresh blueberries and shelled pistachios with a spatula, ensuring even distribution throughout the dough.
Using a cookie scoop or tablespoon, drop rounded balls of dough onto a parchment-lined baking sheet, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown and the centers are set but still soft.
Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely.
