In a large bowl, with a hand mixer, cream the butter, brown sugar, and granulated sugar together on high speed until well mixed, about 2 minutes.
¾ cup unsalted butter, ¾ cup brown sugar, ¼ cup granulated sugar
Beat in the eggs and vanilla extract until creamy, about 2 minutes. Set aside.
2 large eggs, 1 teaspoon pure vanilla extract
In a large bowl, whisk together the flour, dry pudding mix, cocoa powder, baking soda, cornstarch, and salt.
2½ cups all-purpose flour, 3.9 ounces chocolate instant pudding mix, 2 tablespoons unsweetened cocoa powder, 1 teaspoon baking soda, 1 teaspoon cornstarch, ½ teaspoon kosher salt
Pour the dry ingredients into wet ingredients and beat just until combined. Do not overmix or your cookies won’t be the right chewy texture.
Stir in the melted chocolate just until combined.
4 ounces semisweet chocolate
Fold in the semisweet chocolate chips until combined.
1 cup mini semisweet chocolate chips
Using a 2-tablespoon-sized cookie scoop, scoop evenly sized cookies onto a parchment-lined baking sheet. All cookies should go on a single baking tray so they can be placed into the freezer before baking. Cookies can be close together for this step but not touching. Cookies should be shaped into rounded balls – do not flatten cookies. Use your hands to press the dough together if it starts drying out before you’ve formed all cookie balls.
Place the cookies in the freezer for 10 minutes. This will help the cookies to not spread too much during baking.
Preheat oven to 350°F. Line a second baking sheet with parchment paper.
Take about 8 cookies out of the freezer and place them on the baking sheet 3 inches apart. It is important to only bake 1 tray of cookies at a time.
Bake each tray of cookies for 10 to 12 minutes, or until cookie edges seem set. Do not overbake – the tops will still appear a bit underdone, and that’s okay. They’ll continue to bake on the hot tray after removing the cookies from the oven. Overbaking these cookies will cause them to dry out and they won’t have the fudgy texture.
Let the cookies cool completely on baking sheets.