Cut seitan into chunks and grind in a food processor with TVP (or cut all chunks very small with sharp knife). Combine water with yeast extract.
Boil or steam potatoes until soft then mash. Sauté onion and garlic until transparent. Add ketchup, savory, celery seed, allspice and pepper then combine all ingredients and mix well.
Pour mixture into a lightly oiled 9" pie pan. Top with the phyllo sheets, each brushed lightly with olive oil. Trim edges and tuck in. Cut 4 slits for steam to escape. Bake at 350F for 50 minutes.
Serve hot with vegetables and gravy or cold with salads.
*For a more savory flavor, substitute sage or thyme for allspice.
Variations: Use phyllo dough to make a bottom crust as well as a top crust, or substitute pastry dough instead.