• Preheat the oven to 350 degrees F.

Prepare the cookie dough

• Cream together the margarine, butter and sugar until pale yellow and sugar is no longer visible.
• Add the ricotta cheese into the butter/sugar mixture and mix until blended.
• Add the eggs and vanilla extract and mix until blended.
  
• In a medium bowl, sift together the flour, salt, baking soda and baking powder.
  
• Slowly add the sifted flour mixture into the ricotta mixture, about 1/2 cup at a time and mix until blended.
  

Bake the cookies

• Line baking sheets with silicone pads or parchment paper.
• Using cookie scoops, drop tablespoon size amounts of cookie dough onto the lined baking sheets.
• Bake in the preheated oven for 12 minutes or until the bottom of the cookies turn pale brown. The tops of the cookies will NOT be brown.
  

Prepare the buttercream frosting

• Add vanilla extract and salt to the melted butter.
• Gradually add the confectioner's sugar, stirring thoroughly after each addition using a hand mixer.
• Stir in milk, a little bit at a time, just until the consistency of the frosting becomes evenly spreadable. If the icing becomes too runny, add more confectioner's sugar to thicken it.
  

Frost the cookies

• Cool the cookies a bit before applying frosting to them, so that the frosting doesn't melt as you are applying it.
• Using a kitchen knife, top each baked cookie with the buttercream frosting.