In a mixing bowl, combine the softened unsalted butter, brown sugar, and granulated sugar. Use a spatula to cream them together until the mixture is light and fluffy. This process incorporates air into the butter, which helps create a tender texture in the cookie dough.

Add the vanilla extract and salt to the butter-sugar mixture, and mix until well combined.

Gradually add the sifted all-purpose flour, mixing until just combined. Do not overmix, as this can lead to a tougher dough.

Fold in the mini chocolate chips using a spatula, ensuring they are evenly distributed throughout the dough.

Spread the cookie dough mixture evenly onto a baking sheet lined with parchment paper, pressing it down to create an even layer. Place it in the refrigerator to chill while you prepare the chocolate coating.

In a microwave-safe bowl, combine the semi-sweet chocolate chips and coconut oil. Microwave in 30-second intervals, stirring after each interval until the chocolate is completely melted and smooth. This method prevents the chocolate from burning.

Remove the cookie dough from the refrigerator and pour the melted chocolate over the cookie dough layer, spreading it evenly with a spatula.

Sprinkle additional mini chocolate chips on top of the melted chocolate for extra texture and decoration.

Place the baking sheet back in the refrigerator for about 30 minutes, or until the chocolate has fully set.

Once the chocolate is set, remove the bark from the baking sheet and break it into pieces. Serve immediately or store in an airtight container in the refrigerator for up to one week.