Just as when we say “Italian seasoning”, there was no set list of ingredients, rather just the spirit of an idea that you attempted to capture. It may well be that various merchants selling it would even have kept their ingredients secret.
It is a mix you would have on hand, just as we would have curry powder and “poultry seasoning” on hand today.
Ingredients suggested now for it include black pepper, cinnamon, cloves, cubeb, alingale, ginger, grains of paradise, long pepper, mace, nutmeg, etc.
Here’s one interpretation:
1 teaspoon cloves
1 teaspoon fresh nutmeg
1 teaspoon mace
1 teaspoon black pepper
1 teaspoon grains of paradise
3 teaspoons long pepper
6 parts pumpkin pie spice to 1 part black pepper
Literature & Lore
Powder-forte… seems to be a mixture likewise of the warmer spices, pepper, ginger & etc. pulverized… it is called strong powder…”. Samuel Pegge, “The Forme of Cury – A Roll of Ancient English Cookery”. 1790.
Means “strong powder”.