In a large mixing, bowl combine the vegetable oil, melted chocolate, sugar, and vanilla until smooth.
Add in the eggs one at a time, mixing after each addition.
In a medium mixing bowl, stir together the flour, baking powder, and salt. Add flour mixture into the chocolate mixture and mix until combined.
Cover the cookie dough and refrigerate for 3 hours or overnight.
Preheat your oven to 350 degrees F. Line baking sheets with parchment paper or silicone baking mats, set aside.
Use a cookie scoop to scoop the cookie dough into 2 tablespoon portions. Roll the cookie dough into balls. Place one mini peppermint patty into the center of each dough ball and roll again making sure that the patty is completely covered by cookie dough.
Pour the powdered sugar into a shallow bowl. Roll each cookie dough ball in the powdered sugar so that it's covered.
Place dough balls on the prepared baking sheets about 2 inches apart. Bake for 10 minutes.
Remove from the oven and allow the cookies to cool for 5 min on the baking sheet. Then transfer them to a wire rack to cool completely.