Adjust an oven rack to the middle position and preheat the oven to 350F [180C]. Grease three 6 by 2 in [15 by 5 cm] cake pans and line the bottoms with parchment paper. Alternatively, you could make this a single sheet cake by greasing a 9x13 cake pan.
In a medium bowl or liquid measuring cup, whisk together the egg whites, coconut milk, crème fraiche, vanilla, and coconut extract.
In the bowl of a stand mixer fitted with a paddle, whisk together the flour, granulated sugar, baking powder, and salt by hand until combined. With the mixer running on low speed, add the butter one piece at a time, beating until the mixture resembles coarse sand. With the mixer still running on low speed, slowly add a little more than half of the wet ingredients. Increase the speed to medium and beat until the ingredients are incorporated, about 30 seconds, With the mixer running on low speed, add the rest of the wet ingredients, mixing until just combined. Increase the speed to medium and beat for 20 seconds (the batter many still look a little bumpy). Scrape down the sides and bottom of the bowl, add the chocolate chips, and use a spatula to mix the batter a few more times.
Divide the batter between the prepared pans. Tap the pans gently on the counter twice to help get rid of any air bubbles. Bake for 25 to 32 minutes (if you are making the sheet cake version, bake for 35 minutes and then check if wooden skewer comes out clean), rotating the pans halfway through, until the cakes are golden brown and a wooden skewer or toothpick inserted into the center comes out with a faint bit of crumbs, or a finger gently pressed into the top leaves a slight indentation.
Transfer the pans to a wire rack and let cool for 20 minutes, then turn the cakes out onto the rack, remove the parchment paper, and let cool completely. Once cool, the cakes can be frosted or wrapped in plastic wrap and refrigerated overnight.