Preheat the oven to 175C/350F.
Line and grease a loaf tin.
Place the eggs in the bowl of a kitchen stand mixer and beat for 5 minutes, or until fluffy.
Add the maple syrup and vanilla extract and beat on high until smooth.
Place the avocado in a blender and puree until smooth. Add to the mixture, beating on high.
In a separate bowl, sift together the dry ingredients.
Fold the dry ingredients into the mixture.
Add the juice and zest and stir until combined.
Pour into the loaf tin and bake for 55 minutes, or until cooked through.
Allow the loaf to cool in the tin before serving.