For the Cookies

• In a mixing bowl, whisk the flour, baking powder, cream of tartar, and salt. Set aside.
• in the bowl of a stand mixer with the paddle attachment, cream the butter and sugars for 3 minutes.
• With the mixer on low, stream in the oil until combined.
• Add the vanilla, egg, egg yolk, sour cream, lemon juice, and lemon zest. Mix until combined.
• Mix in the dry ingredients 1/2 at a time until just combined. 
• Cover the bowl with plastic wrap and chill for 30 minutes.
• Preheat the oven to 350 and line two cookie sheets with parchment paper.
• Use a large 3 TBSP cookie scoop to portion the dough and roll it into a ball in your hands. 
• Bake 5-6 cookies per sheet at 350 for 10 minutes. 
• While the cookies are still hot use a measuring cup or a flat bottomed glass to flatten the cookies to 1/2″ thick creating the crinkled edges. Allow cookies to cool completely on the hot cookie sheet.

For the Lemon Cream Cheese Frosting

• Use a hand mixer to cream the butter and cream cheese until smooth.
• Add the powdered sugar 1/2 at a time and mix until smooth.
• Mix in the vanilla, lemon juice, and lemon zest.
• Once cookies are cooled, dust with powdered sugar.
• Then, use a 1 TBSP scoop to top the cookies with the frosting and use an offset spatula to spread almost to the edges of the cookies, leaving the crinkled edges exposed.