Preheat oven to 350 degrees. Lightly grease bottom and side of a 9-inch cast iron skillet with 2 tsp of softened unsalted butter. Set aside. In a mixer fitted with a flat paddle, combine remaining room temperature unsalted butter, white sugar, brown sugar and maple syrup on medium speed.

Add vanilla extract then the eggs, one at a time. In a bowl, combine 2½ cups flour, baking soda and regular salt. On medium-low speed, slowly add flour mixture to the butter/egg mixture. With mixer on low, add chocolate pieces and chips.

In a small pan, place caramel pieces and heavy cream. Put on low heat. Slowly melt to combine, stirring often. Caramel pieces and cream can also be melted in a microwave, checking every 15 seconds, stirring until melted.

Dip fingertips in the remaining 2 tbsp flour. Press half of dough into cast iron pan using floured fingertips. Drizzle melted caramel on the dough. Sprinkle with ¼ teaspoon coarse sea salt.

Divide the remaining dough into thirds. Press each piece between your lightly floured hands to form 5-inch by 1/3-inch disks. Place the disks on top of the dough-filled cast iron pan. Using floured fingertips, press dough disks to completely cover the bottom layer of dough and caramel sauce. Making the dough into flat disks helps makes it easier to press remaining dough on top of caramel. Sprinkle top with remaining sea salt.

Place skillet on center rack of preheated oven. Bake for 30 minutes or until a toothpick comes out clean when placed in the center of the cookie. Be careful not to over-bake. The cookie will firm up as it cools.

Let rest 30 minutes. Cut into wedges. Serve with vanilla ice cream.