Preheat oven to 400 F. Place the portabellas gill side up on a baking sheet and bake on the center rack for 5 minutes.

Meanwhile, heat the olive oil in a large nonstick saut pan. Add the shiitakes, onion, and corn, then cook over high heat for about 4 minutes, or until mushrooms are limp. Add the toasted pine nuts and turkey, then cook for 1 minute more.

Spoon the mixture evenly into the portabella caps, making sure that the caps lay as flat as possible on the sheet and the mixture is lower in the center of the caps and higher around the edges.

Crack one egg over the center of each mushroom. Season to taste with salt and pepper. Return mushrooms to the oven and bake until the eggs are cooked. If the eggs do not seem to be cooking, change the settings to medium broil and broil briefly. Once cooked, serve immediately.