Make the lemon curd: In a large bowl, mix together eggs, egg yolks and sugar together. In a medium saucepan, melt butter over low heat. Stir in the egg mixture along with the lemon juice and zest. Stir until thickened, about 10-15 minutes. Pour into a jar and let cool. Cover and place in fridge until firm.
Make the cookies: In a large bowl, mix together the flour with baking powder. Using an electric stand mixer, beat eggs with sugar at medium speed. Slow to low speed and add milk and butter. Add flour mixture to egg mixture 1/2 a cup at a time and continue to beat until well combined. Let dough rest for 15 minutes before rolling.
Preheat oven to 350 degrees. Prepare two baking sheets lined with parchment paper and set to the side. Using a teaspoon, scoop a generous amount of cookie dough and roll with hands into 1" round balls. Place balls onto baking sheet about one inch apart. Press the top of each ball lightly to make a disk shaped mound. Bake in oven for 15-17 minutes until bottoms begin to brown. Cookie will stay pale colored on top.
With a small spoon, scoop the inside of the cookies out to make room for the lemon curd.
In one bowl, mix together yellow and orange food coloring with peach schnapps to make the body base color of the peach. Mix red coloring into the other bowl of peach schnapps until desired shade is achieved to give peaches a blushed look.
With a small paintbrush, brush the bottom edge of each cookie with the pinkish coloring and use the yellow orange mixture to color the body of the peach. Finish by dusting each cookie with sanding sugar.
Fill the finished cookies with the lemon curd and sandwich together, leaving some of the curd visible in between. Garnish the top of each "peach" with a vanilla bean stem and small mint leaves.