In a large bowl, sift together all-purpose flour, salt and baking powder. Set aside.
Combine butter, milk, vanilla extract and orange zest in a saucepan and place it on the burner until the butter is melted.
Pour the butter mixture in a bowl. Add eggs to it.
Take a bowl and toss the blueberries with 1 tablespoon of flour.
Add the butter mixture to the dry ingredient and mix until just combined together.
Fold in the blueberries to the batter. Leave some blueberries aside to decorate the muffins.
Using an ice-cream scoop, scoop out the batter into the muffin liners.
Decorate with blueberries on the top.
Put the muffin tin in the middle rack of the oven tray. Bake at 400 F for the first 6 minutes and then reduce the temperature o 375 and bake for another 11 - 13 minutes
Insert a wooden skewer in the middle of the muffins to test if it is baked properly. If the skewer comes out with a few crumbs (without any liquid), the muffins are ready.
Notes
Do not OVERMIX: Do not overwork the batter. It will develop gluten resulting in harder, gummier and tougher muffins, which we want to avoid.Frozen Blueberries: If you are using frozen blueberries, DO NOT thaw them. Just take them out of the freezer and use. Scoop Out the Batter: Use the regular Ice-cream Scoop to fill in the muffin liners. It gives me equal amount of muffin batter in each liner, helping to be consistent with the size of the muffins.Coat the Blueberries in Flour: You need to coat the blueberries in small quantity of all-purpose flour in order to make sure they do not sink in the bottom of the muffin liners.