Preheat oven to 350 degrees F, 175 degrees C.

Base:

Cream butter with brown sugar in large bowl. Add eggs one at a time, beating well after each egg addition. Add vanilla and beat well.

In a medium sized bowl, combine flour with baking soda. Add flour mixture to butter mixture in 2 additions, mixing well until no dry flour remains.

Separate dough into 2/3 and 1/3. Place the 1/3 dough in the medium bowl used for the flour. Add chocolate chips to the 2/3 dough portion and mix well.

Butter and flour a 12' by 10' baking pan. Spread 2/3 dough portion evenly on bottom of baking pan. Bake for 4 minutes and remove from oven.

Caramel:

Add sugar with 1/2 cup water in a pot over medium heat. Boil until bubbles turn into an amber colour. Remove from heat and add condensed milk. Stir well until blended.

Top the base evenly with the warm caramel. Crumble the 1/3 remaining dough mixture evenly overtop of the caramel. Bake at 350 F for 12-14 minutes, or until edges of the dough are golden. Let cool for 5 minutes.

Melt Chocolate over low heat. Drizzle evenly overtop of cooled cookie caramel square. Cover pan with foil and cool for about 3 hours until cutting into squares and serving.