To toast hazelnuts: Preheat oven to 325° F. Spread nuts on an ungreased cookie sheet and bake for 5 to 7 minutes, stirring often; rub off the papery skins. Coarsely chop nuts and set aside.
To prepare shortbread: Preheat oven to 350° F. Cut 1 1/2 sticks butter into 1/2-inch cubes. Combine butter, 2 cups flour, 1/2 cup brown sugar and salt, and mix until small clumps form. Sprinkle mixture into 9-by 13-inch pan; pat evenly onto bottom and partway up sides. Bake 15 to 20 minutes until golden brown; set aside.
To prepare chocolate layer: Melt chocolate and butter together in a double boiler, stirring occasionally. Stir in condensed milk and salt until smooth. Spread over shortbread crust.
To prepare oatmeal-hazelnut layer: In a large bowl, cream together the 1 stick of butter and 1 cup brown sugar until fluffy. Add egg and vanilla extract; cream again. Add 1/2 cup plus 1 tablespoon flour, baking powder, salt, cinnamon, oatmeal, whole-wheat flour and toasted hazelnuts and mix gently. Add lemon zest and mix gently. Set aside.
To assemble: Sprinkle the evenly over the crust, then drizzle the half-jar of caramel sauce over the coconut. Stir jam to make it spreadable, then smooth it over the caramel sauce. In a microwave warm marshmallow creme, stirring occasionally, to make it spreadable, then smooth it over the jam.
Using fingers, crumble spoon-size pieces of hazelnut-oatmeal mixture on top of creme; do not completely cover top - allow other layers to bubble through. (Leftover mixture can be made into drop cookies, baked on ungreased cookie sheet for 8 to 10 minutes).
Bake bars for 10 to 15 minutes, turning pan several times as it bakes. Cool completely. Use hot knife to cut.Makes 8 to 10 Source: