In a moderately hot skillet add the olive oil and diced onions. Cook until starting to become transparent.
Add the spinach until warm and well mixed with the onions, then add the nutmeg and stir through.
Take the skillet off the heat then stir through the crumbled feta.
Preheat the camp oven to 350 degrees F (180 degrees C).
Combine the melted butter and olive oil.
Work with 3 sheets of phyllo at a time, and leave the remaining sheets covered with a damp cloth. Brush each sheet with the butter mixture, then stack onto the previous one. Cut the phyllo lengthways into 4 strips.
At the end of each strip add 2 tablespoons of the spinach and feta filling. Fold the pastry over the filling to create a triangle holding the filling. Continue to fold the filling over in a triangle until all the pastry is used. Repeat until all the strips and sheets of phyllo pastry are used.
Place the spinach and feta triangles evenly spread on a baking tray(s). Place in the preheated oven and cook for 20 minutes or until golden brown. Serve hot.