We love Spanokopita, which is a Greek spinach casserole. To make this dish more portable and easier to handle, I sometimes make Spanokopita Spinach Triangles. To make them, you have to work fast.
First of all, prepare the spinach filling, using this recipe.
Cut the whole stack of thawed filo lengthwise into quarters, so that each strip is 3 1/2 inches wide. Working with 1 filo strip at a time and keeping the others covered with a lightly damp towel, place the filo strip on a dry work surface. Brush it thoroughly with the melted butter.
Place about 1 Tbs. of the filling 1 inch from the bottom edge. Fold the lower right corner of the pastry up and over the filling, forming a triangle. Roll the triangle straight forward, then again on a diagonal. Continue folding, forming a triangle each time, until you reach the end of the strip. Transfer to a prepared baking sheet and brush the top of the triangle with a little more butter. Use the remaining filo and filling to make the remaining triangles, placing them on the baking sheet.
Bake the triangles until golden brown, about 20 minutes. Let cool for 10 minutes (the filling will be very hot), then serve. This makes 28 warm bites.
This is the diagram of how to do it:
The unbaked triangles can be frozen for up to 1 week in airtight containers, separated by layers of parchment or waxed paper. When you are ready to serve them, bake them straight from the freezer, adding 5 minutes or so to the baking time.