Preheat the oven to 325 degrees. Line 2 baking sheet with parchment paper. Set aside.
In a small bowl, combine both flours, baking powder, and salt. Set aside.
Combine the granulated sugar and lemon zest in a medium-sized bowl or stand mixer. Mix them well then add in the butter. Cream until the mixture is light and fluffy. Mine took about 2-3 minutes.
Add vanilla and lemon juice to the bowl. Mix to combine.
Next, add the flour mixture and mix to combine.
Using a portion scoop or another spoon, scoop your cookies onto the cookie sheet. These cookies do spread a bit, so make sure to give them space. Each cookie will need about 3-4 inches of space, depending on how big your scoop was.
Place in oven. These cookies will take about 9-12 minutes. I like to test them based on color. Specifically the color around the edges. You want it to be just barely golden brown. The centers will still feel pretty soft, but don't worry about that. The edges are the most important indicator. The exception would be if you like a crispy cookie. In that case, make sure the edges are a solid golden brown.
Remove from the oven and allow the cookies to cool for 5-10 minutes.
Once they are cooled, mix the powdered sugar and lemon juice. If you want a glaze like mine, make sure the glaze is thick. Add in more lemon juice or powdered sugar as needed.
Drizzle the glaze over the cooled cookies. Then sprinkle with the remaining lemon zest.