Preheat oven to 375 degrees. Lightly grease a baking sheet and set it aside. 

Rinse the mushrooms, discard the stem and gills, and set them aside. 

Place the cream cheese, cheddar cheese, parsley, and cayenne pepper, if used, in a bowl and blend the ingredients thoroughly. 

Fill each Portobello cap with equal amounts of the mixture.

Prepare three bowls, one with potato starch, one with the eggs and one with matzo meal. 

Working with one mushroom at a time, dredge each filled mushroom in the potato starch, then into the egg mixture, then into the matzo meal, making sure to coat the entire surface each time. Place the coated mushrooms, filling side up, on the prepared baking sheet. 

Bake for about 30 minutes or until the cheese is hot and runny and the crust is lightly browned.

We like using PHILADELPHIA Cream Cheese.