Preheat oven to 175°C (350°F). Grease and line a 2lb loaf tin.

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

In a large bowl, beat butter and sugar until pale and fluffy.

Beat in the eggs one at a time, then stir in orange zest.

Add half the dry mix, then the milk and orange juice, then the remaining dry mix. Stir until just combined.

Fold in chocolate chips if using.

Spoon batter into tin, level the top, and bake 55–65 minutes, until a skewer comes out clean.

Cool in the tin for 10 minutes, then transfer to a wire rack.

Make the ganache.

Place the cream in a small saucepan and heat gently until just steaming (don’t let it boil).

Put the chopped chocolate in a heatproof bowl. Pour the hot cream over and let sit for 2 minutes.

Stir slowly until the chocolate melts and the mixture becomes glossy.

Stir in the orange zest and orange juice.