• Preheat the oven to 350° F. Line baking sheet with parchment paper and set aside.
• In the stand mixer bowl of a stand mixer, add the butter, oil, granulated sugar and powdered sugar. Sprinkle the baking soda, cream of tartar and salt across the top of the sugars evenly.
• Mix on medium speed with the paddle attachment until well-combined, about 1-2 minutes. Scrape down the sides of the bowl as needed.
• Add the sour cream, eggs and vanilla. Continue mixing for an additional 1-2 minutes until combined. Slowly add the flour until combined. Don't over mix.
• Scoop the dough into golf ball sized balls. Place several inches apart on the baking sheet. Add 3 tablespoons of sugar onto a plate. Use a glass to flatten the cookies by dipping the bottom of the glass into the sugar and then pressing each ball about 1/2 inch thick.
• Bake the cookies for 9 minutes or until just set. Don't allow the cookies to get brown. They will be soft, that is what you want. Set the cookies on a rack to cool completely.

For the frosting:

• In a large bowl, beat the butter and cream cheese until smooth. Add the vanilla extract, peppermint extract, and salt. Beat well. Add the powdered sugar until the frosting is smooth.
• When the cookies are cool, frost each cookie. Sprinkle with crushed candy canes.