For the Brownie:
4 ounces unsweetened chocolate, finely chopped
1 cup unsalted butter, at room temperature
2 cups light brown sugar
4 eggs
2 teaspoons vanilla extract
1 cup all-purpose flour

For the Cookie Dough:
¾ cup unsalted butter
¾ cup light brown sugar
¾ cup granulated sugar
3 tablespoons whole milk
1½ teaspoons vanilla extract
1½ cups all-purpose flour
1½ cups mini chocolate chips