Prepare a plate with 4-5 paper towels and set aside.
Use a large soup pot and turn the burner to high heat. Heat the olive oil and then add the spinach. Cover and cook for 1 minute.
Uncover the pot and continue to cook the spinach until the leaves are a bright green and wilted. About 2 minutes, stirring lightly.
Working quickly, use a colander to drain the spinach then pour the spinach onto the paper towel lined plate.
Once the spinach has cooled enough to handle, squeeze out as much liquid as possible. Use a cutting board to coarsely chop the spinach.
In a small bowl, combine the salt, pepper, cayenne pepper, and nutmeg.
Over medium heat melt butter in a large skillet. Add the shallots to the butter and stir until they just turn a golden brown, (about 3-4 minutes)
Add the seasoning mixture and the heavy cream. Increase the heat to medium high and cook until the sauce has reduced by half. (about 5 minutes) Add the lemon zest and stir.
Once the sauce has reduced, toss in the chopped spinach. Reduce the heat to low and cook until the spinach is heated through. Stir while heating so the spinach is evenly coated.
Add the Parmigiano-Reggiano cheese into spinach mixture. Stir the cheese into the spinach until is evenly incorporated. Serve immediately.