1 3/4 cups unsalted butter, divided
1 cup semisweet chocolate chips
2 1/2 cups sugar, divided
3 eggs
2 teaspoons vanilla extract, divided
3/4 cup cocoa powder
1 1/3 cups all-purpose flour, plus 3/4 cup
1/2 teaspoon salt, divided
2/3 cup brown sugar
1/4 cup milk
1 1/2 cups mini chocolate chips
Preheat oven to 350 degrees Fahrenheit and grease a 9" x 13" casserole dish.
Place 3/4 cup of the butter, semisweet chocolate chips, and 2 cups of sugar in a double boiler. Warm gently until melted, stirring regularly.
When chocolate mixture has melted, beat eggs in a large bowl. Slowly add in the chocolate mixture, whisking constantly so you don't cook the eggs.
Add 1 teaspoon of vanilla extract to the chocolate mixture and stir.
In a separate bowl combine 1 1/3 cups flour, cocoa powder, and 1/4 teaspoon salt. Whisk to combine.
Add the dry ingredients to the wet ingredients and stir well.
Pour this mixture into the prepared casserole dish.
Place the casserole dish into the preheated oven and bake for 30 minutes, until a toothpick inserted into the center comes out clean.
Remove brownies from the oven and let them cool completely.
When ready, place the remaining cup of butter, remaining 1/2 cup of white sugar, and brown sugar into the bowl of a stand mixer. Beat for 5 minutes, until light and fluffy.
Add in milk and remaining teaspoon of vanilla extract and beat for another minute or so.
Add in 3/4 cup of flour, remaining 1/4 teaspoon of salt, and the mini chocolate chips. Mix until all ingredients are well combined.
When the brownies have completely cooled, press the cookie dough onto the brownies, pressing them down so they stick onto the brownie.