One of my "tricks" for citrus zest in sweets - I put several tablespoons of the sugar from the
recipe in my handy chopper, add the zest and grind them together until the zest is almost invisible. It seems to really release the fragant oil and distribute it through the batter when added. I actually make really good lemon sugar cookies using Betty Crocker sugar cookie mix. I use several extra tablespoons of sugar, the rind from an entire lemon ground as above and then glaze them with powdered sugar and lemon juice.