Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.

In a large mixing bowl, cream together 1 cup of softened unsalted butter, ½ cup of granulated sugar, and ½ cup of brown sugar until light and fluffy.

Add 2 large eggs one at a time, mixing well after each addition, followed by 1 teaspoon of pure vanilla extract.

In a separate bowl, whisk together 2 cups of all-purpose flour, ½ cup of unsweetened cocoa powder, 1 teaspoon of baking soda, and a pinch of salt. Gradually mix into wet ingredients.

Fold in 1 cup of semi-sweet chocolate chips evenly throughout the dough.

Cover the dough with plastic wrap and chill in the refrigerator for at least 30 minutes.

Remove chilled dough and shape about 1 tablespoon into a ball, flatten, and fill with frozen Nutella and marshmallow fluff before rolling back into a ball.

Arrange dough balls on baking sheets, spaced 2 inches apart, and bake for 10–12 minutes.

Let cookies cool on baking sheets for 5 minutes before transferring to a wire rack.