Grease and flour jumbo muffin pan or line with paper liners; set pan aside.

Preheat oven to 400°F.

In a large bowl, sift together the flour, sugar, baking powder and salt; stir until well combined.

In a separate bowl, whisk together the eggs, milk, vanilla and melted butter.

Add the liquid mixture to the dry mixture; stir until just barely combined. (Note: Take care not to overmix the batter at this stage. The batter may look lumpy.)

Carefully fold the blueberries into the batter until well combined. (Tip: To prevent blueberries from sinking to the bottom of the muffins, toss the fresh berries in 1 Tbsp of flour before folding them ingto the batter.)

Fill each muffin liner just over ½ full. (Tip: Do not overfill or the muffins will overflow as they bake!)

Bake at 400°F for 20-30 minutes, or until a toothpick inserted into a muffin comes out mostly clean.

Let muffins cool for about 10 minutes.

For the Sugar Topping, brush tops of cooled muffins with the melted butter. Place sanding sugar in a shallow dish and dip tops of muffins into sugar.