Lightly spray a baking sheet / tray with the cooking spray.
Lay the first sheet of filo pastry onto the baking sheet / tray, spray it lightly with the cooking spray, then place the second sheet on top, spray that lightly and repeat the process until all the sheets are done.
Brush the milk around the edge of the filo pastry sheets.
Microwave / cook the baby spinach as per the bag’s instructions and then drain it thoroughly. My preferred way of doing this is by putting the spinach in a sieve and pressing the water out of it by using the back of a spoon.
Distribute the spinach evenly over the top of the pastry then make a layer of the cherry tomatoes.
Crumble and sprinkle the grated cheese over the top.
Season with salt and pepper.
Cook in the centre of your oven for 10 to 15 minutes until cheese is bubbling. Remove and serve.