Preheat the oven to 350°F (180°C) or 160°C for a fan oven. Grease two 8-inch (20 cm) cake pans and line the bottoms with parchment paper; grease the parchment.
In a large bowl sift together 1 ¾ cups (210 g) all-purpose flour, ¾ cup (75 g) unsweetened cocoa powder, 1 ½ teaspoons baking powder, 1 ½ teaspoons baking soda, and 1 teaspoon salt. Add 2 cups (400 g) granulated sugar and whisk to combine. Set aside.
In a separate bowl whisk together 2 large eggs, 1 cup (240 ml) buttermilk (or milk), ½ cup (120 ml) oil, and 2 teaspoons (10 ml) pure vanilla extract until blended.
Pour the wet ingredients into the dry ingredients and mix gently until just combined. Do not overmix.
In a small heatproof bowl dissolve 1 teaspoon espresso powder (if using) in 1 cup (240 ml) boiling water. Stir the boiling water (with dissolved espresso if used) into the batter. The batter will be thin.
Divide the batter evenly between the prepared pans and smooth the tops.
Bake for about 30 minutes, or until a toothpick inserted in the center comes out clean. Remove from the oven.
Let the cakes cool in the pans on a wire rack for 10 minutes. Run a knife around the edges, invert the cakes onto the rack, peel off the parchment, and cool completely.
Meanwhile make the buttercream: in a stand mixer fitted with the paddle (or with a hand mixer), beat ½ cup (113 g) softened unsalted butter on medium-high for 3 minutes until creamy.
Add ¾ cup (75 g) unsweetened cocoa powder to the butter and beat at medium speed for 2 minutes.
With the mixer on low, add 3 cups (360 g) powdered sugar slowly until incorporated. Increase speed to medium and beat for 2 minutes.
Add 3 tablespoons (45 ml) milk and 1 teaspoon (5 ml) pure vanilla extract and beat for 1 minute. If the frosting is too stiff to spread, add a little more milk a small amount at a time until you reach a spreadable consistency.
Toast 75 g shredded coconut in a dry skillet over medium heat, stirring constantly, until golden brown; transfer immediately to a plate to stop cooking. Alternatively, spread the coconut on a baking sheet and toast in the oven at 320°F (160°C) for about 5 minutes, watching closely so it does not burn. Let cool.
If the cake layers are domed, level them with a serrated knife so the layers stack evenly.
Place one cake layer on your serving plate or cake board. Spread an even layer of buttercream on top (use part of the frosting for this filling).
Place the second cake layer on top. Apply a thin crumb coat of buttercream over the entire cake to lock in crumbs.
Chill the crumb-coated cake in the refrigerator for 20 minutes to set the frosting.
Remove the cake from the fridge and apply the remaining buttercream to fully cover and smooth the cake.
To decorate, place 80 g Cadbury mini eggs in the center of the top of the cake to form a nest. Pile and arrange the toasted coconut around the eggs on the top to resemble a nest, and press the toasted coconut gently onto the sides of the cake so it adheres to the frosting.