Add the blueberries to the flour mixture and gently toss until they are lightly coated. This helps keep them from sinking and bursting too much in the dough.
1 cup fresh blueberries
Make a well in the center of the dry ingredients. Pour in the buttermilk and melted butter.
¼ cup unsalted butter, 1 cup buttermilk
Gently fold everything together with a silicone spatula until the flour is just moistened. Be careful not to crush the blueberries.
If the dough feels too dry or crumbly, add a little extra buttermilk, 1 tablespoon at a time. If it feels very sticky or wet, add a little more flour, 1 tablespoon at a time, until the dough holds together.
Transfer the dough to the prepared pan. Lightly flour your hands and gently press the dough into an even layer about 1 inch thick. Using a sharp knife, lightly score the dough into 16 squares without cutting all the way through.
Brush the top lightly with milk, then sprinkle with coarse sugar if using.
1 tablespoon milk, 1 teaspoon coarse sugar
Bake for 23 to 30 minutes, or until the top is golden brown and the center is baked through.
Let the biscuits cool in the pan for 10 to 15 minutes, then lift them out using the parchment paper. Cut into squares and serve warm or at room temperature.
Notes
Tips and Tricks
Mix the dough gently and only until combined. Overmixing can make the biscuits dense.
Fresh blueberries work best because they hold their shape better than frozen berries.
If using frozen blueberries, do not thaw them first.
Coating the blueberries in the flour mixture helps prevent streaking and sinking.
For the best texture, serve these biscuits the day they are baked.
Store leftovers in an airtight container at room temperature for up to 2 days.