Preheat the oven to 350 degrees.

In a large bowl combine the butter, brown sugar, and sugar. Mix until well combined.

Add in the eggs and mix until combined.

Stir in the vanilla.

In a medium bowl combine the salt, baking soda, baking powder, and flour. Mix well and then add to the sugar mixture. Mix well.

Fold the chocolate chips into the batter.

Add 2/3 of the batter into a 9 x 13 pan and press into the bottom. Set aside.

Meanwhile, add the condensed milk and chocolate chips to a medium saucepan over medium heat. Stir until chocolate is melted and the mixture is smooth.

Remove from heat and pour over top of cookie batter in the pan. Smooth out to the edges.

Take the remaining cookie dough and flatten pieces in between your hands and place on top of the fudge mixture as best you can.

Bake for 25-30 minutes or until the top of the cookie is browned. Remove from oven and cool completely. Place in refrigerator for 20 minutes before cutting.

Cut the cookie into bars and enjoy!