Preheat your oven to 350°F (175°C). Grease the cake pans and line them with parchment paper.

In a bowl, combine flour, cocoa powder, baking powder, baking soda and salt. Whisk them together well.

In another bowl, beat the butter and sugar until light and fluffy. This should take about 3–4 minutes.

Add eggs one at a time. Mix well after each addition. Stir in vanilla extract and orange zest.

Add half of the dry mix to the butter mixture. Pour in half the milk. Mix gently until smooth.

Add remaining dry ingredients and milk. Mix until fully combined. Do not overmix the batter.

Pour the batter evenly into the prepared cake pans. Smooth the tops with a spatula.

Bake for 30–35 minutes or until a toothpick inserted comes out clean.

Remove from oven. Let cakes cool in pans for 10 minutes. Transfer to a cooling rack completely.

Heat heavy cream in a saucepan until simmering. Pour over chopped chocolate. Stir until smooth. Add butter and vanilla.

Place one cake layer on a plate. Spread some ganache over the top. Add second cake layer.

Pour remaining ganache over the top and sides. Smooth with a spatula for even coating.

Refrigerate the cake for 30 minutes. This helps the ganache set perfectly.

Cut into slices and serve. Garnish with orange zest or chocolate shavings if desired.