Grease six individual ramekins (approximately 3½ inches in diameter) or one 9 x 13-inch baking dish.
Melt butter in a large, microwaveable bowl. Stir sugar and salt into the melted butter. Whisk in milk. While whisking, add flour and baking until just combined.
Pour batter into baking dishes. Sprinkle rinsed blueberries onto top of batter. Bake cobbler for 35-40 minutes or until golden brown.