Add flour, sugar, baking soda, salt, and cocoa into an UNGREASED 9x13 pan.
Mix well.
Create three "wells" in the dry ingredients.
In one well, pour the hazelnut extract, in the second, pour the oil, and pour the vinegar into the third well.
Pour water over everything and mix together well.
Bake for 25-30 minutes at 350 degrees.
Cool cake and crumble.
Prepare pudding according to package directions.
In cups, place a layer of crumbled cake topped by a layer of prepared pudding. Add a dollop of hazelnut spread on top of pudding. Add another layer of cake and pudding.
Refrigerate until serving.
Garnish with hazelnut candy or cookies.