Preheat oven to 425 degrees and prepare a muffin pan with twelve baking cups. Lightly spray the cups with nonstick cooking spray.
In a large mixing bowl, use an electric mixer to cream together butter and sugar.
Add the eggs and beat until combined. Mix in the baking powder, salt and vanilla until just combined.
Using a wooden spoon, stir in 1 cup of the gluten free flour until just combined. Add the milk and stir until just combined. Add the remaining flour and stir until combined. Use a rubber spatula to scrape the sides and bottom of the bowl to completely incorporate the flour into the batter.
Add the chocolate chips and use the rubber spatula to fold them in.
Transfer the batter evenly to the 12 baking cups.
Bake at 425 degrees for 7 minutes, then reduce the oven temperature to 350 degrees and continue baking for another 15-18 minutes. The muffins are done when a toothpick inserted into the center comes out clean.
Allow the muffins to cool for 5 minutes in the pan then transfer to a wire rack to cool completely.
Spray the inside of the baking cups with nonstick cooking spray. The cooking spray prevents the baking cups from sticking to the muffins.
Start the baking time at 425 degrees and then lower the temperature to 350 degrees after a few minutes. Baking the muffins at two different temperatures makes all the difference. The higher temperature creates tall, crispy, muffin tops and the lower temperature keeps the insides tender and the bottoms from getting too brown.