Preheat oven to 325°F (160°C). Grease four 5-inch mini skillets.
Whisk together flour, baking powder, and salt. Stir in oats. Set aside.
Using an electric mixer on medium speed, beat the butter and brown sugar until light and fluffy. Add the egg and vanilla, and mix well.
Reduce mixer speed to low. Gradually add the flour mixture, mixing just until combined.
Set aside about 1/2 cup of the dough. Divide the remaining dough among the prepared skillets, spreading evenly and firmly in the bottom of each skillet. Top each with about 2 tablespoons of chocolate-hazelnut spread, and spread evenly over the dough.
To make the topping and assemble:
Drop the reserved dough by teaspoonfuls over the chocolate-hazelnut spread. Sprinkle with chocolate chunks and oats. If desired, sprinkle a pinch of coarse salt on each cookie.
Place the skillets on a rimmed baking sheet lined with parchment paper to catch any spills and to make it simpler to get the cookies in and out of the oven.
Bake 35 to 40 minutes, or until the cookies are golden brown and set. Cool about 10 minutes before topping with ice cream and serving.