Buknade (Medieval English Pottage)

I found this amongst several medieval English recipes I extracted from different editions of medieval manuscripts containing 15th and 16th century recipes. The original recipe calls for hyssop but I doubt it is commonly available, so just leave that out. Also the original suggests chicken or veal as meat but I'll post it with chicken.

• Ready In: 30 mins
• Serves: 6
• Yields: 6

Ingredients

• 3  sprigs parsley
• 3  sprigs hyssop
• 3  leaves sage
• 5  cups  chicken stock
• 1  pinch mace, ground
• 1  pinch clove, ground
• 1  pinch saffron
•  salt
• 12  ounces chicken, cooked
• 3  egg yolks
• 1⁄2 teaspoon cider vinegar
•  white pepper, to taste
•  ground ginger, to taste

Directions

1. Chop parsley, hyssop if available and sage leaves without stems.
2. Place chopped herbs, spices and stock in a saucepan, bring to a gentle simmer.
3. Shred chicken (without skin), add to simmering stock.
4. Beat egg yolks.
5. Carefully beat some of the hot stock into the yolks, beating constantly, then pour yolks slowly into pan, stirring, on very low heat.
6. Add vinegar, pepper, ginger and salt to taste.
7. Serve immediately.