• Combine butter, oil, sugars, and lemon extract.
• Blend in the eggs.
• Add flour, salt, cream of tartar, and baking soda until incorporated.
• Cover bowl and refrigerate for 1 hour.
• Preheat oven to 350° F.
• Roll dough into golf ball-sized balls. Fit 6 on a baking sheet.
• Bake 8-9 minutes until done. Do not overbake.
• Let cool on baking sheet 1 minute before removing to cooling rack.

Lemon Buttercream Frosting

• Beat butter until it is smooth.
• Gradually mix in the powdered sugar.
• Add lemon juice and lemon zest; mix until combined.
• Add milk, a few drops at a time until frosting is thin enough to spread.