Preheat the oven to 300°F.
Line a baking sheet with aluminum foil and spray with cooking spray.
Melt the butter in a dutch oven, add the onion, and cook over low heat, stirring occasionally, until soft and tender. Season your onions. Add prosciutto, peas, and chicken stock, and cook about 10-15 minutes until liquid evaporates.
Season more with seasonings listed above, or of your choice, to taste, if needed, and remove from heat.
Add in the ham, heavy cream, and egg yolk. Mix well to combine, and add back to heat and cook for a few more minutes.
Fill pastry shells with the pea and ham mixture and place in oven for 5 minutes.
*If you wish, before adding to the oven, grate a little parmesan cheese on the top of pastry shells.
*Save any leftover filling for a good soup or pot pie (Pot pie will be linked to the page of this recipe)
