If you don't like/can't find Tofutti, firm regular tofu would probably make a decent alternative. Press/drain it, then puree smooth, mix in some lemon juice, and adjust the other seasonings as needed until you like the flavor.
1. Sautee 2 minced garlic cloves in 2-3 tbsp. margarine or olive oil and a splash of white wine.
2. In the resulting garlic-wine-marg, sautee 2-3 handfuls washed baby spinach until bright green and wilted.
3. Add the entire contents of the pan to 4 oz. Tofutti cream cheese and mix well.
4. Stir in a handful of finely chopped toasted nuts, and enough toasted breadcrumbs to reach a moist-but-not-sticky consistency.
5. Season as desired--I used about 1 heaped tbsp. mixed Italian herbs, 2-3 tbsp. nutritional yeast, and some salt and pepper. Cover and refrigerate a while so flavors can mingle.
6. Wash and de-stem 16 oz. white mushrooms or baby portobellos. Fill each with a generous scoop of filling (you want a sort of "heaping" effect). Dip the filled side in breadcrumbs.
7. Grease the bottom of a round cake pan with oil or marg and a splash of wine. Arrange the mushrooms, filled side up, in the pan and cover with foil.
8. Bake at 350F until the mushrooms are soft and have given off some liquid. (I think mine took at least half an hour.) Then nom away.