Prepare Peppers:  Cut peppers in half lengthwise.  Seed and core.  Bring  a large pot of water to a boil.  Drop the peppers into the water and wait about 2 minutes.  Remove with tongs and drain on paper towels. 

Prepare filling:  Let spinach thaw in a colander over the sink or a bowl.  Dry it well and put into a bowl.   Sauté the onion in 3 tablespoons olive oil until translucent.  Add the garlic and stir to mix and heat garlic through.  Add nutmeg (freshly grated is preferred) and remove from heat.  Pour warm onion mixture over the spinach.  Add cream cheese and mix well to create a spinach paste.  Add parmesan cheese and mix again.

Putting it together:  Heat olive oil over medium high heat in a flat bottomed large fry pan.  Fill peppers with a spoon and smooth off the top.  Gently place pepper into fry pan filling side down.  This will provide the "crust" to keep the filling in.  Fry for about 5 minutes and then gently turn the pepper over and fry on the other side.  Fry until the pepper is soft it slightly caramelized on the bottom.  Remove from the pan and place in a oven safe pan.  Glass is great.  At this point the peppers can be stored in the refrigerator.  They are great hot, warm, room temperature and cold.  Put them on a hard roll for a great sandwich.  To reheat, put the pan into a preheated 350° oven for 20 minutes.  May also be heated in the microwave.