Preheat oven to 425F. Place nine muffin liners in a 12-cup muffin pan.
In a medium-sized bowl, whisk together the almond flour, cornstarch, cinnamon, baking powder and salt.
In a large bowl, use an electric mixer on medium-high speed to beat together the eggs and brown sugar until foamy, about 1 minute. (You don't want it to thicken. You just want bubbles to form on top).
Add the oil and vanilla and mix until just combined.
Add the dry ingredients to the wet mixture and use a spatula to stir until just combined.
Gently fold in the chocolate chips.
Divide the batter into the 9 muffin liners, filling them almost to the top. Add more chocolate chips on top (if desired).
Bake at 425F for 5 minutes, then reduce the temperature to 350F (without opening the oven door) and bake for another 8-10 minutes, or until a toothpick inserted into a muffin comes out clean.
Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
Notes
Use muffin liners. I prefer to use liners for most muffin recipes to prevent them from sticking to the pan and browning too much on the sides and bottom. Parchment liners are my favorite for not sticking to the muffin.
Don't overmix the batter. This pretty much goes for all batters, but I say it again because you don't want tough or dense muffins. After the wet ingredients are mixed together, switch to a spatula to stir in the dry ingredients and chocolate chips.
Be careful not to overbake. Almond flour browns quickly so keep an eye on the muffins. If they overbake even for a minute or two, they will end up a bit dry.