This delicious recipe is courtesy of Michael Lomonaco.
Heat a nonstick skillet over low heat. Add bacon and cook until crispy, about 8 minutes. Transfer bacon to a paper-towel-lined plate to drain; reserve bacon fat. When bacon has cooled, crumble and set aside.
Fill a large saucepan with 2 inches of water. Fit with a steamer basket. Bring to a boil over medium-high heat, then reduce to a simmer. Add spinach to steamer basket, cover, and steam until wilted, about 2 minutes. Transfer spinach to a colander set over a large bowl to drain, reserving drained water; let cool slightly.
Place butter and 2 tablespoons reserved bacon fat in a heavy-bottomed saucepan. Heat over medium-high heat until melted and beginning to bubble. Whisk in flour, and cook, whisking, until well combined, 2 to 3 minutes. Whisk in cream and bring to a boil over high heat. Reduce heat and let simmer until thickened, 2 to 3 minutes.
Add spinach and cook, stirring occasionally, 5 minutes. Add some of the reserved spinach water if mixture seems too thick. Season with salt, pepper, and nutmeg; stir in bacon. Transfer creamed spinach to a serving bowl; serve immediately.