Preheat your oven to 375°F (190°C). Line a muffin tin with paper liners.
In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, whisk together the melted butter, eggs, milk, and vanilla extract.
Pour the wet ingredients into the dry ingredients and mix until just combined. Do not overmix.
Fold in the chocolate chunks.
Divide the batter evenly among the muffin cups.
Bake for 20 minutes or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.