Heat oven to 350° F.
Line your cake pans with parchment circles and spray with not stick cooking spray. I sometimes skip the parchment circles because I’m awful, but I’d recommend it to be safe.
Sift together the baking powder, baking soda, flour, and powdered milk. Stir in the salt. Set aside.
Cream first six ingredients in a stand mixer fitted with a paddle attachment on medium speed until very pale and fluffy, about 5 minutes. Scrap down bowl about halfway through, making sure to get the bottom too.
Turn mixer to low and add egg whites in two additions. Scrape down bowl.
Pour coconut milk and buttermilk into one measuring cup. With the mixer still on low add in flour mixture and the buttermilk-coconut mixture, alternating between the two in about three additions. As soon as last addition is added turn off mixer and fold with a spatula to make smooth. Don’t overmix or you’ll make your cake tough. Just no clumps.
Pour into your chosen cake tin, about halfway up. Don’t do what I did in one test and fill your mini cake tins 3/4 the way and have them a) not bake properly and b) floff over.
Depending on the cake size bake on the middle rack between 15-25 minutes. Start testing with a cake tester on the low end. You don’t want to overbake. Overbaking makes cake meh. & who wants meh cake? A cake tester should come out clean, as in no goo but a few crumbs are ok.
Meanwhile make the soak. Mix all of the ingredients very well in a bowl and set aside. Mix again before pouring.
Cool cakes in the pan about five minutes and then turn them out onto wire racks to cool. If splitting the layers, I like to chill my cakes after they’ve fully cooled on the racks to make cutting easier. I’m not really an expert on icing cakes, to be honest. I kind of wing it. If stacking layers on chantilly, chill a topped layer before topping with another layer or it can will squish out. I would know. Less so with a mini cake, but still, to be safe.
Once mostly cool (a little warm is okay) or once out of the fridge and split, place the cake in a baking dish and poke holes all over it with a cake tester.
Spoon about 1 cup of the leches mixture over the each layer (for 8″ layers). Use half a cup for smaller layers. It may seem like a lot, but it will take it. I kind of spoon it in the middle and spread it around to keep it from running off, for maximum soak upage. Let layers sit in the fridge, covered for an hour.
Make Frosting. Whip the heavy cream (halve this if you’re making a two layer cake) with the cream of coconut, coconut extract, and vanilla until it begins to thicken. Add in confectioner’s sugar and whip to stiff peaks, being careful not to over whip.
Stack and ice cakes as desired. Reiterating tips for using chantilly: top a layer, set it in the fridge for about half an hour, then top with another layer. Also, I don’t spread it all the way to the edges as I find it will spread when topped. I usually leave about an inch around the edge. Top with toasted coconut if using. Best served with a glass of local milk!