In a shallow pot, heat the ¼ cup olive oil and sauté the 4 fresh spring onions and the 1 leekfor a few minutes.
Preheat oven to 180℃.
Add the 1 lbs fresh spinachand continue sautéing for a few minutes until all the liquid evaporates.
Sprinkle with 3 tbsp fresh dill, 2 tbsp fresh parsley, salt, and pepperemove the pot from the heat.
In a large saucepan, mix the 5 cups milk with the ⅔ cups cornflour and the butter until the cornflour dissolves. Sprinkle half of the 1 cup cheese mix and stir until the sauce thickens.
Transfer the mixture to the heat and stir.
Once the cream thickens, remove the pot from the heat and slowly incorporate the 1 cup cream cheese stirring until they melt.
Add the 2 eggs, stirring quickly so they blend evenly, and the ½ cup butter.
The last step is to add the sautéed ingredients and mix until well combined.
Pour the mixture into the baking dish and sprinkle the surface with the remaining grated cheese mix.
Bake the spinach gratin at fan setting, on the middle rack, for about 40 minutes.
Remove the baking dish from the oven and let it cool before cutting it into pieces.