Preheat oven to 400 degrees. Place portobello caps, gill sides up, in a large baking dish and bake 5 minutes. Meanwhile heat oil in a large saute pan over high heat. Add shiitakes, onion, and corn; saute until mushrooms are limp and corn tender, 3-4 minutes. Add pine nuts and bacon if using and stir well. Be sure to season well. Remove mushrooms from oven and evenly divide shiitake mixture among 4 caps smoothing surface. Make sure caps lay as flat as possible so that eggs do not slide to one side while baking. Crack 2 eggs on top of each mushroom.
Lightly salt eggs and return dish to oven. Bake until eggs are done to your liking, then serve at once. Nutritional info per serving: 485 cal; 19g pro, 39g carb, 32g fat (55%)