In an 8-inch non-stick saute pan, render duck skin or bacon over medium heat to crisp cracklings. Remove and set aside on paper towels and pour off all but 1 tablespoon of duck fat. Add onion and cook until softened (about 8 to 10 minutes). Add pine nuts and endives and cook 2 minutes until endives have softened. Add eggs and cheese and season with salt and pepper and stir well with pine nut mixture. Allow eggs to set on bottom by cooking without stirring 2 minutes and place in oven. Cook 8 to 9 minutes, or until eggs have set but are not dried out. Remove from oven, flip out onto plate and allow to cool.
To serve plain, slice into wedges like a pie and serve, sprinkling over pine nuts and cracklings or use as contorno for stuffed duck neck dish.