Preheat your oven to 375°F (190°C) and grease a 9-inch round baking dish.

Combine blueberries, granulated sugar, lemon juice, lemon zest, cornstarch, ground cinnamon, and salt in a bowl. Toss gently.

Pour the mixture into the greased baking dish and dot with pieces of unsalted butter.

In a mixing bowl, whisk together flour, sugar, baking powder, baking soda, and salt.

Cut the remaining unsalted butter into the dry mixture until it resembles coarse crumbs.

Stir in buttermilk and vanilla extract until a soft dough forms. Do not overmix.

Dollop the biscuit dough over the blueberry filling, spacing spoonfuls apart.

Brush the tops with buttermilk and sprinkle with coarse sugar if desired.

Bake for 35-40 minutes until biscuits are golden brown and filling is bubbling.

Cool for 10-15 minutes before serving, enjoying warm with vanilla ice cream.