Preheat oven to 400 °F. Spray a 12-cup muffin tin with cooking spray OR grease with solid shortening OR line with paper cupcake liners.
Combine flours, starches, sugar, salt, baking powder in a bowl. Add in chocolate chips and stir so that all the chips are coated in flour.
In a second bowl, mix the milk, oil and egg. Add to bowl with dry ingredients, and stir until thoroughly combined.
Spoon into muffin tins, filling about 2/3 full. Bake for 20-25 min. Remove from oven and allow to cool 5-10 minutes before removing from pan.
You can use any "milk" sub here (soy, rice, etc.), but I find coconut gives the best texture. If you don't have a milk allergy, you can also substitute regular cow's milk. Whole milk will give a better texture than skim, but skim can be used.
For coconut milk, I use unsweetened So Delicious in the green-label refrigerator carton or shelf-stable Tetra-Pak container. You could substitute the vanilla version as well.
If making egg free, substitute 1/4 cup applesauce. Mix it into the milk so that it distributes easily into the flour mix.
You can also use solid shortening (i.e. Crisco, Spectrum) instead of liquid oil. Use 1/4 cup shortening and "cut in" the fat to the flour etc. using a fork, until the mix contains pebble-like bits of fat incorporated throughout the flour. Combine just the milk and egg together and then add liquid to flour/etc and shortening mix and continue as above.
Coconut: Although classified by the FDA as a tree nut, coconut is not a common allergen and is not related to tree nuts. If you have a tree nut allergy, consult your physician to find out if you need to avoid coconut.
Corn Substitutions: Corn is a common ingredient in products. Starch, modified food starch, dextrin and maltodextrin can be from corn. Consult with your physician to find out which corn derivatives you need to avoid. Many corn-free options are available in the US. Find out more about corn substitutions.
Egg Substitutions: There are many egg-free products and foods available to make your recipes free of eggs. Find out more about egg substitutions.
Gluten: Gluten is a protein found in specific grains (wheat, spelt, kamut, barley, rye). Other grains are naturally gluten-free but may have cross-contact with gluten-containing grains. Look for certified gluten-free products if you need to avoid gluten. Find out more about wheat and gluten substitutions.