Preheat the oven to 350°F and line a cookie sheet with aluminum foil.
In a mixing large bowl or stand mixer fitted with a paddle attachment, beat together the 1 cup granulated sugar, ½ cup black cocoa powder, ½ cup salted butter, 3 tablespoons vegetable oil, 1 large egg, and 2 teaspoons vanilla extract until well mixed.
Mix in the 1⅓ cups all-purpose flour, 1 (3.4 oz.) box instant vanilla pudding mix, ½ teaspoon baking powder, and ½ teaspoon salt, until a thick dough forms.
Mix in the ½ cup mini chocolate chips.
Divide the dough into 6 (5-ounce) balls and place the onto the cookie sheet. Chill in the fridge for 30 minutes for puffier cookies or bake right away for firmer cookies.
Bake for 10 to 12 minutes. You want the cookies just baked so they stay soft.
Cool on a cooling rack.
While the cookies cool, prepare the 16 ounces chocolate frosting if using homemade. Then frost the cookies once they are cooled.
Crush the 9 Oreos in a Ziploc bag with a rolling pin
Sprinkle the Oreo crumbs on each cookie. Pressing them down gently so they sink into the frosting a bit.
Top the cookies with the 12 gummy worms, adding 2 to each cookie, or more if you'd like.