Preheat oven to 160 c / 325 f
Butter and grease a 8 x 4 inch loaf pan. Line the bottom with parchment (optional)
In a bowl , whisk together the flour , cocoa , sugar , baking powder , baking soda and salt
In a small bowl or cup , whisk together the curd , egg , oil and vanilla.
Add the liquid mixture to the dry flour mixture and whisk just until combined ( no flour seen )
Pour into prepared pan and bake for 18 to 24 minutes until a toothpick inserted in centre comes out clean.
Cool in pan for 5 minutes
Remove from pan and cool completely on wire rack