Preheat the Oven: Preheat your oven to 450°F. Pour the melted butter into the bottom of a 9-inch baking dish and set aside.
Mix Dry Ingredients: In a large bowl, whisk together the flour, sugar, baking powder, and salt until well combined.
Add Buttermilk: Gradually pour in the buttermilk while gently stirring the mixture. Stir just until combined; the dough will be sticky and slightly lumpy. Avoid overmixing.
Fold in Blueberries: Gently fold in the fresh blueberries, ensuring even distribution throughout the dough without crushing them.
Shape and Cut Biscuits: Pour the dough into the baking dish over the melted butter. Evenly spread and smooth the dough with a spatula. Using a sharp knife, score the dough into 9 squares by making two cuts down each side.
Bake: Bake the biscuits in the preheated oven for 25-30 minutes, or until the tops are golden brown and a toothpick inserted into the center comes out clean.
Prepare the Glaze: While the biscuits bake, whisk together powdered sugar, vanilla extract, and 1 ½ tablespoons milk in a small bowl. Add more milk a teaspoon at a time until the glaze reaches your desired consistency.
Glaze Biscuits: Once the biscuits are done baking, let them cool for a few minutes. Drizzle the glaze over the warm biscuits.
Serve: Cut or pull apart the biscuits and serve warm. Enjoy!