Preheat the over to 180ºC
Boil the conchiglioni as per the instructions on the packet. Drain and put aside
Meanwhile wilt the spinach. Wash the spinach and drain off excess water. Add 1 tbsp of olive oil to a large pan and heat to a medium high heat. Add the spinach and stir frequently. When the spinach has reduced and all leaves wilted, drain off any excess water. Add a dash of salt and a sprinkle of black pepper and blitz the spinach with a stick blender
Break the feta into small pieces in a medium sized bowl. Add the wilted spinach and stir through so evenly distributed.
Tip the conchiglioni into the oven dish and using a dessert spoon, fill each piece of conchiglioni with the mixture. Leave the filled conchiglioni face up in the dish.
Sprinkle the pesto over the surface, add the Kalamata olives and sprinkle with the pine nuts.
Bake in the oven for 15 minutes and serve immediately.