Preheat your oven to 375°F (190°C) and line a mini muffin pan with paper liners or lightly grease the muffin cups with non-stick cooking spray.
In a medium bowl, whisk together the flour, baking powder, and salt until well combined.
In a separate large bowl, mix together the melted butter, brown sugar, greek yogurt, egg, and vanilla extract until smooth and well combined.
Add the dry ingredients to the wet ingredients and stir until just combined. Be careful not to overmix, as this can lead to tough muffins.
Fold in the mini chocolate chips, reserving a few to sprinkle on top of the muffins before baking.
Using a small cookie scoop or spoon, fill each muffin cup in the mini muffin tin with batter, filling each cup full. Use a rubber spatula to get all the batter from the bowl. Sprinkle the remaining chocolate chips on top of the muffins.
Bake the muffins for 10-12 minutes until they are golden brown, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the pan for a few minutes before transferring them to a wire rack to cool completely.