Preheat oven to 400 degrees F. In a small bowl, combine melted butter, flour, sugar, salt, and vanilla extract. Spoon together until little crumbles form and place in the freezer.
Combine melted butter, sugar, brown sugar, and vanilla extract. Whisk together until combined. Then add eggs, Greek yogurt, and buttermilk. Continue to whisk together until smooth.
Add flour, baking powder, and kosher salt. Fold with a flat spatula or spoon. Add blueberries and continue to fold together until a smooth batter forms.