Preheat an oven to 190 degrees C. Lightly grease a baking tray. Mix the spinach, feta cheese, mozzarella cheese, Parmesan cheese, garlic and salt in a bowl.
Arrange one sheet of filo pastry on a clean work surface and brush with melted butter. Cover the remaining filo pastry with a damp towel. Place a second sheet of filo on top and brush with butter, then place a third sheet on top. Cut the buttered filo lengthways into four strips.
Place about 1 tablespoon of the spinach mixture on the bottom of each strip. Take the bottom right corner and fold the pastry over the filling to make a triangle. Fold the bottom left corner up to make another triangle. Continue folding until all the pastry is folded. Arrange the stuffed triangles, seam-side down, on the prepared baking tray. Lightly brush the triangle with butter. Repeat with the remaining filo pastry and spinach filling.
Bake in the preheated oven until golden brown, about 20 minutes. Cool slightly before serving.
Nice easy recipe. I didn't have frozen spinach so used fresh spinach and wilted it to bring down the volume. Only used one packet of spinach which came to 230g as I was only feeding 5, but I left the cheese amounts the same because I like it :-) this worked well. - 01 Oct 2013