Soak dried mushrooms in enough boiling water to cover about 15 minutes or until soft. Drain, discarding liquid. Squeeze mushrooms to remove additional liquid; finely chop mushrooms.
Meanwhile, in a medium skillet, cook fresh mushrooms in hot oil over medium-high heat about 5 minutes or until liquid is evaporated. Add porcini mushrooms, parsley, and garlic; cook and stir for 1 minute. Remove from heat. Sprinkle with salt and pepper.
In a medium bowl, combine egg yolk, ricotta cheese, and mushroom mixture. Cover and chill until needed.