Hawaiian Chantilly Layer Cheesecake Cake

New York Style Cheesecake Layer:
3 (8 oz.) packages cream cheese, room temperature
1 cup + 2 tablespoons white sugar
1/2 cup + tablespoon milk or soy milk
3 eggs, room temperature
3/4 cup 0% Greek yogurt (I used plain Chobani; may also sub higher-fat yogurt or sour cream)
2 teaspoons vanilla extract
3 tablespoons all-purpose flour
Chocolate Chiffon Cake:
1/2 cup unsweetened cocoa powder
3 tablespoons instant coffee granules (optional)
3/4 cup boiling water
1 cup + 6 tablespoons all-purpose flour
1/4 cup cornstarch
1 3/4 cup white sugar
1 1/2 teaspoon baking soda
1 teaspoon salt
7 eggs, separated, room temperature
1/2 cup oil
2 teaspoons vanhilla extract
Chantilly Frosting:
Original recipe from Guava Rose
3/4 cup + 2 tablespoons butter, melted
3/4 cup evaporated milk
3/4 cup white sugar
1 teaspoons vanilla extract
1 egg, room temperature
1 egg yolk, room temperature
1 tablespoon cornstarch
Whipped Chocolate Frosting:
2 cups heavy whipping cream
1/4 cup + 1 tablespoon unsweetened cocoa powder
1/4 cup + 1 tablespoon white sugar
1 tablespoon + 1 teaspoon vanilla extract
1 cup sweetened coconut flakes

For the cheesecake:
Preheat oven to 350 degrees. Fill a 9x13-inch baking pan with boiling water and place it on the bottom rack of your oven.
Lightly grease an 8-inch springform pan and set aside.
In a large mixing bowl, cream together cream cheese and sugar until very light and fluffy, with no lumps remaining.
Stir in milk.
Add eggs one at a time, stirring in until just incorporated. Do not overbeat.
Stir in yogurt, vanilla, and flour until mixture is just combined and smooth.
Pour batter into prepared 8-inch pan and place it on the top rack, above the water bath. Bake in preheated oven for 55 minutes, then turn off oven. Do not open the oven door at this point. Allow cheesecake to sit inside oven for another hour before removing and transferring to refrigerator; the gradual cooling will prevent your cheesecake from cracking. (If your cheesecake does crack, there’s nothing to worry about: it’ll be stuffed inside scrumptious layers anyway!)
Allow to chill completely (at least 3 hours) before slicing into 3 separate, even layers.
For the chocolate cake:
Preheat oven to 325 degrees F. Lightly grease an 8-inch springform pan and set aside.
In a medium bowl, stir cocoa powder and coffee granules into hot water until dissolved. Set aside and allow to cool completely.
Using a colander, sift flour and cornstarch together into a large bowl. Mix in sugar, baking soda, and salt. Set aside.
In a separate bowl, whisk together egg yolks, oil, and vanilla. Gently fold this mixture, along with the cooled cocoa mixture, into the dry ingredients until smooth.
In another grease-free bowl, beat egg whites with a hand mixer until they form stiff peaks, about 3-4 minutes. You should be able to tip over the bowl without the meringue sliding out. Fold egg whites into batter.
Pour 1/4 cake batter into prepared pan. Bake for 10-15 minutes, until toothpick inserted in center comes out clean. Allow cake to cool before removing to a cooling rack, then refill with another 1/4 batter and repeat until you have four prepared cake layers. (Alternatively, you may bake all your batter at once and then slice the resulting cake into four layers, but make sure you adjust baking time accordingly!)
Wrap cooled cakes in cling wrap and place in freezer until ready to use.
For chantilly frosting:
Combine all ingredients except cornstarch in a medium saucepan over medium-low heat.
Allow mixture to come to come to a slow boil, then continue stirring occasionally and boil mixture for another 2 minutes before removing from heat.
Quickly whisk in cornstarch, taking care to continue whisking until mixture is completely smooth. If lumps appear, strain your mixture through a sieve.
Refrigerate for at least 2 hours before using.
For whipped chocolate frosting:
Place all ingredients in a food processor. Blend for about 15 seconds, until frosting stiffens and becomes just spreadable.
For assembly:
Spread coconut flakes on a baking sheet and bake in a preheated oven (at 250 degrees) for 10-15 minutes, stirring occasionally, until flakes become golden. Remove from oven and allow to cool as you assemble your cake.
Remove all cake and cheesecake layers from refrigerator/freezer. You should have 4 chocolate cake layers and 3 cheesecake layers. (If you do not, use a serrated knife at this time to slice your cakes into the appropriate number of layers.)
Place one chocolate cake layer onto a large serving plate. Carefully top with a cheesecake layer, then continue layering until you have seven alternating layers.
Frost entire cake with whipped chocolate frosting using an offset spatula. If desired, frost a circle around the top of the cake to hold in the chantilly frosting, which may leak slightly.
Gently spread chantilly frosting on top of frosted cake.
Top with toasted coconut flakes.