20 ounces
frozen spinach, thawed, drained, liquid squeezed out
Method
Melt the butter in a large skillet over medium heat. Add the shallot and cook until softened but not browned, about 3 minutes. Add the garlic and cook, stirring, until fragrant, about 1 more minute.
Stir in the heavy cream, mustard, salt, pepper, garlic powder, nutmeg, and cayenne and bring to a simmer. Reduce the heat to medium-low and cook until the cream has thickened enough to coat the back of a spoon, about 5 minutes.
Add the Parmesan and spinach and stir to combine. Cook, stirring, until thickened and creamy, about 5 minutes longer. Serve warm.