Adjust the oven rack to middle position and preheat oven to 175°C/350°F (standard oven setting). Line two 8-inch springform pans with baking parchment (buttering the springform collar will help the parchment stick to the sides of the pan).
In a medium-sized bowl, combine the sugars, oil, egg and vanilla. Using a mixer fitted with the whisk attachment, mix until the mixture looks well combined, about one minute.
Dissolve the coffee granules in the water, then stir in the buttermilk. Set aside.
In a small bowl, stir together the flour, cocoa powder, baking powder, baking soda and salt.
Add the wet and dry ingredients to the egg and sugar mixture. Gently stir the ingredients together, using a rubber spatula or a spoon. Once you’ve incorporated most of the dry ingredients, mix briefly with the mixer until the batter is smooth, about 15 seconds. Using the back of a spoon, divide and spread the batter evenly in and over the prepared pans.
Bake the cakes for 20 minutes, or until a tester inserted into the centre of the cakes comes out clean. Remove from the oven and allow the cakes to cool to room temperature completely in the pans. This should take about 30-60 minutes. Don’t skip this step! It’s very important that the cakes are cool, otherwise the meringue won’t crisp up! Make sure the bottom of the springform pans and the top of the cakes feel cool to the touch before you proceed with the recipe.
In the meantime, make the raspberry filling:
Combine frozen raspberries, sugar and water in a small saucepan. Heat over low heat, stirring until the sugar has dissolved and the berries have started to release their juices. Crank the heat up to medium-high and allow to come to a boil, stirring occasionally.
Cook for two minutes over low heat, stirring occasionally. Remove from heat and allow the raspberry sauce to cool completely.
Once the cakes are cool, make the meringue:
Adjust oven rack to middle position and preheat oven to 120°C/250°F (standard oven setting).
Add the egg whites and vanilla to a spotlessly clean, medium-sized bowl. Using a mixer fitted with the whisk attachment, beat the egg whites until they hold soft peaks. With the mixer still running, gradually add the sugar, one tablespoon at a time. Once you’ve added all the sugar, keep mixing for another 5-10 minutes, or until you can no longer feel any sugar crystals when you rub a bit of the meringue between your fingers and the meringue can hold stiff peaks.
Divide the meringue evenly over the cool cakes. Use the back of a spoon to push the meringue against the lined collars of the springform pans. Use a spoon to smooth the meringue in one of the pans, and to swirl the meringue in the other pan to form peaks.
Bake for 40 minutes or until dry and crisp. An easy way to check whether the meringue is done, is gently tapping it with a fingernail; the meringue should sound hollow.
Remove the pans from the oven and allow the cakes to cool for 10 minutes in the pans. After 10 minutes, carefully remove the springform collar and peel away the baking parchment from the sides of the cakes. There is no need to remove the bottom part of the pans yet. Allow the cakes to cool completely.
Once the cakes have cooled, whip up the cream. In a medium-sized bowl, mix together the cream and sugar until the mixture holds stiff peaks.
To assemble the cake:
Place the flat meringue layer onto a cake stand or serving plate, meringue-side down.
Fill a pastry bag fitted with an open tip with the whipped cream and pipe a ring of small mounds or dollops around the outer edge of the chocolate cake layer. Spread the remaining cream onto the center of the cake and spread it smoothly all over the top of the cake layer, out to the inner edges of the ring of whipped cream dollops.
Spoon about three tablespoons of the raspberry sauce onto the center of the cake layer, on top of the smoothened whipped cream layer. Again, smooth over the top of the cake layer, out to the inner edges of the whipped cream dollops.
Place the second cake layer cake-side down on top of the raspberry filling. Press down lightly. Strain the remaining raspberry sauce through a fine-meshed sieve and drizzle it over the top of the cake. Scatter a few raspberries on top.
Serve at once, or refrigerate for up to eight hours in an airtight cake container. Remember that whipped cream doesn’t hold well.
Notes
Raspberry sauce can be made up to three days ahead and stored in an airtight container in the refrigerator until needed. Cake layers can be made a day ahead and stored (in the pans!) in an airtight container at room temperature. Cake-meringue layers can be made a day ahead and stored in an airtight container at room temperature.
I suggest you make the raspberry sauce and cake layers a day ahead, so both can cool thoroughly overnight. The next day, whip up the meringue to finish the chocolate-meringue layers, then assemble the cake after the layers have cooled.
Recipe by The Tough Cookie at https://thetoughcookie.com/2015/12/24/chocolate-meringue-layer-cake-with-raspberries-and-cream/