In a gallon zip top bag or medium bowl, mix together the flour, baking powder, baking soda, and salt. Set aside.
Cream the butter and sugar together with an electric mixer until aerated, pale yellow and very fluffy, 5+ minutes (this is called "Mechanical Leavening"). Scrape bottom of the bowl frequently.
Beat in the egg, lemon zest, lemon juice, vanilla, and poppy seeds. Turn the mixer on low and slowly add in half the flour mixture. Scrape the bowl, add the rest of the flour and stir gently by hand until combined, being careful not to overmix. Refrigerate overnight ideally or at least a few hours.
To bake, preheat oven to 350 and line baking sheet with parchment paper. Use a cookie scoop or 1.5 tablespoon portions, to form perfectly round balls. Place them two inches apart. Bake for 8-10 minutes, until they are slightly underdone in the center.
Remove from oven and leave cookies on the pan to cool for at least 5 minutes before transferring to a cooling rack. While cookies are still cooling on pan, squeeze lemon wedges over the tops of the cookies, about 5-6 drops per cookie, distributed evenly over the tops.