Heat olive oil in a large skillet over medium heat.  Add the minced shallot and green onion and saute until soft, about 2-3 minutes.  Add the minced garlic and cook until fragrant, about 1 minute.

Next add the chopped spinach and fresh herbs to the skillet.  Stir until the spinach is wilted.  Season with salt and pepper.  Just a pinch of salt will do since the feta is salty.

Add the feta cheese and stir until incorporated.  Remove from the heat.

Heat a clean skillet over medium heat.  Butter one side of the bread and place it butter side down in the hot skillet.  Add a slice of mozzarella cheese, then 1/4 cup of the filling and another slice of mozzarella, then the top piece of bread with the butter on top.

Cook the grilled cheese for about 4 - 5 minutes until the cheese is melted and gooey, then flip the grilled cheese and cook for another 4 minutes until the bread is golden and the cheese is melted.

Enjoy.