Preheat your oven to 350°F. Grease or line a 12-cup muffin tin and set it aside.
In a large bowl, place the flour, xanthan gum, baking soda, salt, cinnamon, granulated sugar, and brown sugar, and whisk to combine well, working out any lumps in the brown sugar. Add the carrots, and stir to combine.
Create a well in the center of the dry ingredients and add the melted butter, oil, eggs, pumpkin and vanilla, and mix to combine. The mixture should be thick and moist, but not at all stiff.
Add most of the chocolate chips, and stir until they’re evenly distributed throughout the batter. If you’d like, reserve a few chocolate chips to place on the tops of the batter once it’s transferred to wells in the muffin tin.
Fill the wells of the muffin tin completely with the batter, and shake the tin back and forth to redistribute the batter into even layers in each well.
Scatter any remaining chocolate chips evenly over the tops of the dough and press gently to help them adhere.
Place the muffin tin in the center of the preheated oven and bake until the muffin tops spring back when they’re pressed gently in the center, about 25 minutes.
Allow to cool about 10 minutes in the pan, and then transfer to a wire rack to cool completely.