Place the chopped chocolate in a tall heatproof container or a stand blender.

Add the cream and peanut butter to a saucepan. Heat over medium heat until the first bubbles appear, whisking occasionally to help the peanut butter blend in.

Pour the hot cream mixture over the chocolate. Using an immersion blender, blend until the chocolate has melted and the mixture is fully emulsified. A whisk works too, although a blender gives a smoother result, so a stand blender is a good option if you do not have an immersion blender.

Once the ganache looks fully combined, transfer it to a clean bowl and press plastic wrap directly onto the surface.

Refrigerate for at least six hours or overnight.

Remove from the fridge and let it stand at room temperature for 10 to 20 minutes to soften.

Whip for about 10 seconds or until the color lightens and the ganache becomes fluffy. Do not overwhip. Use immediately to assemble the cake.

Preheat the oven to 160C (320F). Line the bottoms and sides of two 6 inch (15 cm) cake pans with parchment paper.

In a bowl, whisk together the flour, cocoa powder, baking powder, and salt.

In the bowl of a stand mixer fitted with a paddle attachment, or in a mixing bowl with a hand mixer, beat the sugar, butter, and vanilla on medium-high for five minutes until well combined.

Add the oil and beat until the mixture turns pale yellow and fluffy. Add the melted chocolate and mix until incorporated.

Add the egg and beat until the mixture looks smooth and emulsified.

Add half of the dry ingredients and mix just until combined. Add the milk and mix again. Add the remaining dry ingredients and mix until no dry spots remain and the batter looks smooth.

Divide the batter evenly between the pans. Bake for 27–30 minutes, or until a toothpick inserted in the center comes out clean.

Let the cakes cool in the pans until safe to handle, then invert them onto a cooling rack. Cool until just warm.

Wrap each layer in plastic wrap and refrigerate until completely chilled.

Place one layer on a cake stand or plate. Spread a thick ½ to ¾ inch (about 1½ cm) layer of ganache over the top.

Set the second layer on top and frost the outside of the cake with the remaining ganache. There is enough for a semi-naked finish and simple piping on top. If the ganache feels too firm to pipe, transfer it to a piping bag and warm it gently with your hands until soft enough.

Refrigerate the assembled cake for up to four hours or until well chilled before serving.