In a large bowl, stir together the flour, sugar, baking powder, and salt, and set aside. In a small bowl, stir together the milk, melted butter, vanilla extract, and eggs until combined.

Pour the wet ingredients into the dry ingredients, and gently stir together using a spatula until partially mixed, but some flour pockets remain. Add in the pistachios and chocolate, and continue to mix by hand until just combined, being careful to avoid over-mixing.

Cover the batter and rest at room temperature for 30-45 minutes. Don't skip this step- it ensures that you get tall, domed, muffins. While the batter rests, preheat your oven to 400 degrees, and line a muffin tin with liners, or generously grease the pan if not using liners.

Once the batter has rested, scoop the batter into the muffins cups evenly. The batter should come almost to the top of each muffin cup, and there should be enough for 12 standard sized muffins. Generously sprinkle the tops with more sugar, and bake at 400 degrees for 18-20 minutes, or until golden. A toothpick inserted in the center of a muffin should come out with just a few crumbs.

Once the muffins come out of the oven, give them a little twist while they are still warm to ensure they don't stick to the pan. Cool and enjoy!