• Preheat oven to 350 degrees and very lightly grease a baking sheet.
• In a large bowl, cream together butter, vegetable oil, 1 1/4 cups sugar, powdered sugar, heavy cream, and eggs.
• In a second large bowl, whisk together flour, baking soda, cream of tartar, and salt.
• Add dry ingredients to wet ingredients and mix until dough comes together.
• Roll dough into balls (roughly the size of golf balls) and place on greased baking sheet 2-3 inches apart.
• Place remaining 1/4 cup sugar in a shallow dish. Press the bottom of a tall drinking glass into the cookie dough in the bowl (just to moisten the bottom of the glass, no cookie dough should stick to it), then dip into sugar. Press the bottom of the glass into the top of each cookie dough ball to flatten about halfway. (The edge should "break" to create the signature crinkle edge")
• Bake for 8-11 minutes until cookies look dry but not browned. Allow to cool on baking sheet for 4-5 minutes, then transfer to a cooling rack to cool completely. Repeat process with remaining cookie dough.

Frosting

• Cream butter until very light and fluffy (about 2-3 minutes). Add sour cream, salt, and vanilla and mix until smooth. Mix in powdered sugar until incorporated and smooth. Add 2-3 drops of red food coloring and mix well.
• Store cookies in airtight container at room temperature and frosting in airtight container in the fridge. Frost cookies immediately before serving.