Preheat oven to 425 F and spray a 12-cup muffin tin with non-stick spray.
On a lightly flour surface, unfold the thawed puff pastry sheet and roll out with a rolling pin (approximately 10"x11"). Cut into three rows, and then cross-wise in four rows to make 12 squares.
Carefully place one of the squares into each of the muffin tin cups, pressing down into the bottom and up the sides, with the corners hanging over the top slightly.
Whisk eggs (add 2 tablespoons of milk for a little fluffier scrambled eggs). Heat a medium, non-stick skillet over medium heat and add eggs. Cook, stirring every so often, and breaking up, until the eggs are scrambled and cooked through.
Remove from heat and stir in ham and chopped spinach.
Fill each muffin tin cup near the top with the ham, egg and spinach mixture, then cover the tops with cheese. Fold the corners over and pinch together.
Place in oven and bake for 12 minutes, until puff pastry is golden brown and cheese is bubbly. Allow to cool for a minute or two and then serve and enjoy!