Mix together 4 cups water and 5 heaping teaspoons of Roasted Chicken Base. Set aside.
Place Prosciutto and 5 Tablespoons water into a cooking pot. Select Sauté/Browning and cook until water has almost evaporated. Add 2 teaspoons olive oil. Use a spatula to break up Prosciutto and cook until crisp, approximately 6 minutes. Be careful not to let the Prosciutto burn.
Remove prosciutto to a plate lined with a paper towel. Chop with a sharp knife when cool and set aside.
Add butter and swirl it around to melt. Add shallots and mushrooms and cook until shallots are soft and liquid has evaporated. Add ½ cup marsala and garlic and sauté for about five minutes. Add the rest of the marsala, salt, marjoram, and pepper and bring to a simmer.
Mix in chicken broth. Place chicken into the pot and add thyme.
Lock on the lid and close pressure valve. Cook at high pressure (most machines default to high pressure) for 3 minutes.
When beep sounds, wait 10 minutes and then release pressure.
Remove lid, discard thyme twigs and remove chicken to a cutting board. Remove ½ cup of liquid and add potato starch (or xanthan gum if making this keto) or . Whisk to form a slurry. Pour slurry into soup and mix.
Use an immersion blender and blend until soup is smooth. Cut chicken into chunks and return to soup.
Ladle into bowls and top with shaved asiago cheese and crumbled prosciutto. Garnish with parsley.
Make sure to use a good marsala wine, not one that is labeled for cooking. A good marsala is one that you would enjoy drinking or that others may enjoy drinking.Wild Mushrooms are delicious in this soup. Mix them up with some cremini mushrooms.If you cannot find wild mushrooms, use all cremini mushrooms.