Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish.

Combine butter and chocolate in a large saucepan over medium-low heat. Melt chocolate, stirring frequently. Remove from heat and stir in white sugar. Stir in eggs and vanilla extract. Mix in flour until batter is smooth and pour brownie batter into the prepared baking dish.

Bake in the preheated oven until top is dry and edges have started to pull away from the sides of the pan, 25 to 30 minutes. Let cool completely, about 30 minutes.

Cream butter and brown sugar together in a bowl. Stir in flour, salt, vanilla extract, and chocolate chips. Add water, 1 tablespoon at a time, stirring after each addition until dough reaches cookie dough consistency. Spread cookie dough on top of cooled brownies.