"These delicious cookie brownies are perfect, not too rich and not too bland. It is a brownie recipe on top of a brownie-shaped cookie. My dad tried it and he said it was too good to be true. It may be long but it's worth it!"
Preheat oven to 325 degrees F (165 degrees C). Grease a 9-inch baking pan.
Stir 1 cup all-purpose flour, 1/4 teaspoon baking soda, and 1/4 teaspoon salt together in a bowl.
Cream brown sugar, 6 tablespoons butter, and 1/4 cup white sugar together in a bowl. Stir in 1 egg and egg yolk. Add flour mixture and 1 cup chocolate chips; stir until combined. Spread cookie dough in the prepared baking pan.
Combine 1/4 cup white sugar, 1 tablespoon butter, and water in a saucepan over medium heat. Bring to a boil. Stir in chocolate chips until smooth; transfer chocolate mixture to a bowl. Stir in 1 egg and vanilla extract.
Stir 1/3 cup all-purpose flour, 1/4 teaspoon salt, and 1/8 teaspoon baking soda together in a bowl. Add to chocolate mixture. Spread batter evenly on top of the cookie dough.
Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 21 minutes. Be careful not to overbake.