Duck eggs can be used in any recipe that calls for chicken eggs, but,
because duck eggs are bigger and richer, it will affect the results.
Usually that means the recipe will be even more awesome than usual.
When I wanted to make a pound cake with duck eggs, I decided to go the traditional route of weighing the ingredients. You start with your eggs, weigh them, then add equal amounts, by weight, of flour, sugar, and butter. The blog I followed also suggested a teaspoon of baking powder and I used a dash of Vanilla Extract as well. You can find a detailed description of the recipe Here.