- With the rack in the middle position, preheat the oven to 350°F (180°C). Butter the sides of two 6-inch (15 cm) springform pans with removeable bottoms. Line the bottoms with parchment paper (see note).
- In a bowl, combine the flour, cocoa powder, baking soda and baking powder.
- In another bowl, whisk together the eggs, sugar, oil and vanilla. Add the dry ingredients alternating with the buttermilk. Mix until smooth.
- Divide two-thirds of the cake batter between the two prepared cake pans, about 1 cup + 2 tbsp (280 ml) in each pan. Refrigerate the remaining batter for the third cake layer.
- Bake the two cakes for 40 to 45 minutes or until a toothpick inserted in the centre of the cakes comes out clean. Let cool for 15 minutes. Unmould and let cool completely on a wire rack.
- Clean out and dry one of the cake pans. Butter the sides of the pan and line the bottom with parchment paper. Spread the remaining cake batter out in the pan.
- Bake for 40 to 45 minutes or until a toothpick inserted in the centre of the cake comes out clean. Let cool for 15 minutes. Unmould and let cool completely on a wire rack, about 3 hours.
- Place the chocolate in a bowl.
- In a small pot, bring the cream and corn syrup to a boil. Remove from the heat and pour over the chocolate. Let sit for 1 minute without stirring. Whisk until smooth. Add the butter. Cover and refrigerate for 20 minutes or until chilled but still spreadable. Reheat slightly in the microwave oven as needed before using.
- In a bowl placed over a pot of simmering water, heat the sugar and egg whites, stirring constantly, until the sugar has dissolved. Remove the bowl from the pot. Whisk with an electric mixer until stiff peaks form. The mixture should be lukewarm. Add the vanilla.
- Add one or two pieces of butter at a time while whisking constantly. Continue to whisk for 5 minutes until the mixture is light and creamy (see note). Using a spatula, scrape down the sides and bottom of the bowl a few times (see note).
- Cut off the rounded tops of the cooled cakes to make them as flat as possible. Place one cake on a serving dish. Cover with half of the ganache. Layer on the second cake and remaining ganache. Stack the third cake on top without ganache.
- In three separate bowls, place ¼ cup (60 ml) of the vanilla icing. Add turquoise food colouring to one of the bowls. Add more turquoise colouring to the remaining two bowls to obtain three different shades of turquoise. Set the bowls of coloured icing aside.
- Using an offset spatula, cover the cake in a thin layer of white icing. This will help trap any stray crumbs on the cake. Refrigerate the cake and the icing for 30 minutes.
- Cover the entire cake with the remaining white icing, smoothing it out with an offset spatula. Refrigerate the cake for 1 hour.
- Meanwhile, fold the paper muffin liners into the shape of birthday hats. Secure them in place with some hot glue. Glue a pompom to the point of each hat. Glue the hats to the heads of the dinosaur figurines.
- Using a small offset spatula, apply the three turquoise icings to the cake, alternating tones in no specific pattern. Sprinkle the confetti over the cake in a random pattern. Place two dinosaurs on the top of the cake and the third one on the serving plate. The cake will keep for 3 days, covered, at room temperature.
To avoid wasting the egg yolks, use liquid egg whites. An egg white weighs 30 g and measures 2 tbsp (30 ml). Therefore, you will need ½ cup (120 g) egg whites for this recipe.
If you have three 6-inch (15 cm) cake pans on hand, you can bake the three cakes at the same time.
The mixture may separate after you add about half of the butter. Everything should come together once you add the remaining butter. This step takes time, so don’t add the butter too quickly. If the icing seems too soft when you are ready to apply it to your cake, refrigerate it for a few minutes, then whisk it up again.
The icing can be prepared in advance if left covered at room temperature. Mix it well before applying it to your cake.