• Preheat oven to 350 degrees Fahrenheit. Line an 8x8 inch square pan with parchment paper.

To make the cookie bars:

• Cream together butter and sugar until soft and fluffy.
• Add eggs and vanilla; mix until thoroughly incorporated.
• Add the flour, salt and baking soda. Mix again just until combined, scraping the side of the bowl as needed.
• Stir in chocolate chips.
• Evenly press dough into prepared pan.
• Bake cookie bars until edges begin to golden, about 30 minutes.
• Remove from oven and cool completely.

To make the frosting:

• Cream together cream cheese and butter.
• Add cocoa powder and ½ of the powdered sugar. Mix on low until combined.
• With mixer running on low, add remaining powdered sugar, vanilla, and milk.
• Once all the ingredients have been added, increase mixer speed to medium high and beat until frosting is light and airy, about 4 minutes.

To assemble:

• Evenly spread cookie bars with frosting and garnish with additional chocolate chips, if desired.
• Slice and serve immediately or refrigerate until ready to serve.