• Prepare the dry ingredients.  Whisk together the flour, baking powder, baking soda, and salt in a large mixing bowl. Then, set aside.
  
• Cream the butter and sugar.  In a separate large bowl, use an electric mixer on medium-high speed to beat the softened butter, sugar, and eggs until the mixture is light and fluffy, about 3-5 minutes.
  
• Add the wet ingredients.  Add the sour cream, lemon zest, and lemon juice to the butter mixture. Blend on medium-low speed until fully combined.
  
• Combine the wet and dry mixtures.  Slowly add the flour mixture to the butter mixture, one cup at a time, mixing at low speed until combined. The dough will be very soft.
  
• Chill the dough.  Cover the bowl with plastic wrap and refrigerate the dough for 1 hour to firm up. Towards the end of the chilling time, preheat the oven.
• Preheat the oven and prepare the baking sheets.  Preheat the oven to 375°F (190°C). Then, line baking sheets with parchment paper or lightly coat with cooking spray.
• Shape the cookies.  Using a tablespoon, scoop rounded portions of dough and drop them onto the prepared baking sheets, spacing each cookie about 2 inches apart.
• Bake.  Bake the cookies for 10-12 minutes until the edges and bottoms are lightly golden. If baking multiple sheets at once, rotate them halfway through for even baking.
  
• Cool completely.  Remove the cookies from the oven and let them cool on the baking sheet for 2-3 minutes before transferring them to a wire rack to cool completely.

Frosting

• Prepare the lemon frosting.  While the cookies cool, make the frosting. In a mixing bowl, beat the softened butter, powdered sugar, lemon juice, and lemon zest on medium speed for 2 minutes until smooth and creamy. Then, add 1-2 drops of yellow food coloring for a soft yellow hue.
  
• Frost the cookies.  Once the cookies are completely cool, spread a layer of frosting on each cookie. Serve and enjoy!