Prepare the Oven and Ingredients: Preheat the oven to 450°F (232°C). In a large bowl, whisk together the flour, sugar, salt, and baking powder.
Prepare the Biscuit Dough: Add the cold milk and blueberries to the dry ingredients, mixing just until combined. Freeze the butter for about an hour, then break it into chunks and fold into the dough. Knead gently until the butter is evenly distributed.
Shape and Bake: Roll the dough on a floured surface to ¼ to ⅛ inch thick. Cut out approximately six biscuits using a biscuit cutter. Place on a baking sheet and bake for 7 to 12 minutes, until golden brown.
Prepare the Glaze: Melt 1 tablespoon of butter. In a small bowl, mix powdered sugar, water, vanilla extract, and lemon juice until smooth.
Finish and Serve: Brush the baked biscuits with melted butter and drizzle with glaze. Serve warm.