Bring a pot of salted water to a boil over high heat. Add the spinach and cook for 2 minutes. Drain in a fine mesh strainer, pressing with a large spoon to release as much water as possible. Finely chop and set aside.
Melt the butter in medium saute pan over medium-high heat. Add the shallots and garlic and cook, stirring, until soft and fragrant, about 2 minutes. Add the spinach and cook, stirring, just until the liquid is released. Add the cream, salt, pepper, and nutmeg, and cook until the cream is reduced by half, about 4 minutes. Remove from the heat and serve immediately.