Preheat the oven to 325 degrees F and place the racks in the upper-middle and lower-middle positions. Have 2 parchment lined baking sheets.
In a bowl, cream the sugars and butter, either by hand or with a hand-held mixer, until smooth and incorporated, about 2 minutes. Add in the egg, yolk and vanilla extract. Mix until incorporated. Add in the flour, salt and baking soda and mix until incorporated. Fold in the pecans and chocolate chunks.
Scoop out 1/4 cup of the dough and roll into a ball (or if you have a large ice cream scoop, use that). Place the formed dough balls on the prepared baking sheets, 4 per sheet, and using your hands, press down to flatten. Bake until the edges are slightly golden and the middles are set but still soft, 15 to 18 minutes.
Let the cookies cool for 10 minutes. Then flip them over and coat the bottom of half of the cookies with fudge sauce. Then coat the other cookie bottoms with the caramel sauce.
Place a generous scoop of ice cream on each of the fudge-lined cookies and top with a caramel-lined cookie, lightly pressing together. Repeat with the remaining cookies and ice cream. Roll in chocolate sprinkles. Eat immediately or freeze for later.
Cook's Note: If you freeze the cookies to eat later, just be aware that the cookies get hard. I always like to build 'em fresh if possible so the cookies stay nice and soft.