Preheat oven to 350 degrees F. 

In a medium-sized mixing bowl, mix together flour, salt, baking soda, and cream of tarter; set aside. 

In the bowl of a standing mixer, cream butter and both granulated & powdered sugars together for 2 minutes until fluffy. Slowly stream in the oil while beating. Add the vanilla and peppermint extract and then beat in the eggs one at a time until well combined.

Slowly add the flour mixture to the wet ingredients, mixing until combined (scrape down the sides of the bowl as needed). Mix in sprinkles.

Roll dough into 2 inch balls to make approx. 36 cookies. Place ¼ cup sugar in a small dish. Place rolled dough on a baking sheet about 3 inches apart. Using a drinking glass (or something that is 2.5 inches in diameter), dip into sugar. Press the glass into a ball of dough until it is ½ inch thick (the dough will form a jagged edge and spill past the edge of the glass). Repeat the process of dipping the glass into sugar and pressing it into a ball of dough.

Bake for 8 minutes only. Gently remove cookies from pan onto a cooling rack and let them cool completely. Place them in an air tight Tupperware in the fridge.

Weigh the chocolate. Measure the cream needed for the ganache in a separate bowl. 

Pour the cream into a small saucepan and place it over medium-low heat for a few minutes. It's not necessary to boil or simmer it. It just needs to get hot. Remove the cream from the stove.

While the cream is heating, chop the chocolate into fine pieces. Scoop the chocolate into the cream. Stir gently to distribute the chocolate through the cream and then let it sit for a few minutes to give the chocolate time to soften and melt. With a spatula or wooden spoon, stir the ganache. 

 Cool the ganache slightly and spread over cold cookies and serve immediately or let the ganache dry (it will dry to the touch) and then store in an air-tight container in the fridge. Top each cookie with a chocolate peppermint bark square.