Preheat your oven to 350°F (175°C).

In a medium mixing bowl, whisk together flour, salt, baking soda, and cream of tartar until well combined.

In a stand mixer, beat together softened butter, granulated sugar, and powdered sugar for about 2 minutes until light and fluffy.

Gradually pour in canola oil, then add vanilla and peppermint extract, mixing on low speed for 30 seconds.

Add eggs one at a time, mixing until fully combined and smooth.

Gradually mix in the dry mixture until just combined, and fold in red jimmies sprinkles.

Portion dough into 2-inch balls and place on a parchment-lined baking sheet, spacing them 3 inches apart.

Bake for 8 minutes, until edges are lightly golden. Let them cool on the baking sheet for a few minutes before transferring to a wire rack.

Prepare chocolate ganache by heating heavy cream until hot, then pour it over chopped dark chocolate and stir until smooth.

Once cookies are cool, spread ganache over each cookie and top with Ghirardelli Peppermint Bark square.