Defrost the chopped spinach and phyllo dough sheets overnight in the refrigerator.
Drain the spinach. Using your hands, squeeze all of the excess water out of the spinach. It's very important that the spinach is not wet.
Preheat the oven to 350 F. Add the spinach, vegan feta, just egg (or flax egg), salt, and pepper to a medium mixing bowl. Combine with a spatula until all of the ingredients are evenly combined.
Depending on the type of phyllo dough you use, you'll have either one or two logs. Cut the phyllo log into three 4 inch long pieces.
Carefully roll one of the phyllo dough logs out. Using a tablespoon, or cookie scoop, scoop out the spinach mixture and place it on the corner of the phyllo dough. Using two sheets, fold the dough into a triangle. Then continue folding one side over the other until the sheets are completely used.
Continue placing the spinach on the phyllo dough sheets and folding it into triangles until all of the spinach mixture has been used. Place on a baking sheet lined with parchment paper. You should get about 12-15 triangles.
Add one pat of butter to each triangle. Bake for 10-12 minutes or until golden brown at 350 F on the middle rack.
Allow them to cool for 5 minutes on the baking sheet. Serve warm. Top with optional fresh herbs.