Preheat the oven to 400 degrees fahrenheit
Saute the onions over medium high heat for a few minutes until cooked through and slightly translucent
If using fresh spinach, sautee over a medium heat with a pinch of salt and cook untill wilter. Drain and squeeze dry in a clean kitchen towel. Spinach has a lot of water in it and if you dont ring it out you will have a very watery mixture
Brush one sheet of phyllo dough with the melted butter then repeat with another 3 layers. Cut into 6 equal portions and press into a greased muffin tin. Repeat with the remaining phyllo
Divide the spinach mixture equally between the phyllo cups and bake for 10 minutes till its Golden brown and crispy
Let them cool slightly in the pan for 5 mins then serve
