In the mixing bowl of a stand mixer, add the Butter, Sugar, Egg and Vanilla, and mix together until smooth and creamy.  Juice the Lemon, and add the Juice to the Mixing bowl. Zest the Lemon, and add zest to the mixing bowl, and mix until blended. 

In a separate bowl, add the Flour, Baking Powder, Baking Soda, and Salt, and sift together until completely mixed.  Add to the mixing bowl, and mix until blended and a smooth dough has formed.  Add the Yellow Food Coloring Gel, and mix until well blended. 

Heat the oven to 350 degrees, and line 2 cookie sheets with Parchment Paper. 
Scoop the Cookie Dough with a cookie scoop, and place on the Parchment Paper lined Cookie Sheets (about 12 to a cookie sheet), and bake for 15 minutes, or until the edges are just beginning to brown.  Repeat until all the dough has been scooped and baked. 

Remove Cookies to a wire rack to completely cool.

While the Cookies are cooling, make the Frosting.

In the mixing bowl, place the Butter, Cream Cheese, Heavy Cream, and Vanilla, and mix until smooth and creamy. 

Add the Powdered Sugar a cup at a time, and mix on low speed, scraping down the mixing bowl when needed, until all the Powdered Sugar has been added.  Blend until smooth and thick. 

Place the Frosting in a Pastry bag with a small round tip, and when the Cookies are cool, pipe the Frosting onto the top of the Cookies in a Zigzag, or curvy pattern. 

Allow Frosting to set up or firm up for about 30 minutes. 

Serve, and Enjoy!