Preheat your oven to 400°F and line a muffin tin with muffin liners.
In a small bowl, sift together the flour, pumpkin pie spice, baking powder, baking soda, and salt.
In a large mixing bowl, whisk together the brown butter, brown sugar, and granulated sugar.
Add in the eggs and vanilla and whisk until combined and smooth.
Whisk in the pumpkin puree until fully combined. Next stir in the dry ingredients and the milk until fully incorporated.
Then gently fold in the chocolate chips.
Spoon the batter into your muffin cups so that they are almost full. If desired, press a few extra chocolate chips into the tops of the muffins.
Bake at 400°F for 18-24 minutes for regular sized muffins. Rotate the pan about halfway through so that the muffins brown evenly.
Remove from the oven and let cool on a wire rack.
Notes
For mini muffins reduce the baking time to 15 minutes.Muffins will keep in an airtight container at room temperature for up to 3 days.To Make Brown Butter: Melt unsalted butter over medium heat, stirring frequently. Watch closely for the butter to develop brown specs and a nutty aroma. Once you start seeing brown specs, let cook for just a few seconds longer (watch very carefully or it will burn). Remove from the heat and pour into a small bowl so that it doesn't continue to cook. Set aside and let cool for about 20 minutes in the fridge. Note: For every ½ cup (1 stick or 113g), you'll lose about 1 tablespoon (14g) to evaporation while cooking. So you can either add in an extra 1 tablespoon before browning, or if you're browning big batches, just make up the weight difference in your recipe with regular unsalted butter if needed.