Chop the fresh spinach roughly and set aside. Peel and dice the onion, then mince the garlic.
In a skillet over medium heat, add a tablespoon of oil and sauté the onion and garlic until fragrant and translucent, about 5 minutes. You'll notice a warm, savory aroma fill the kitchen.
Transfer the sautéed onion and garlic to your crockpot. Pour in the vegetable broth and cream or coconut milk, stirring to combine. The mixture should look creamy and light, with a gentle simmering aroma.
Add the chopped spinach to the crockpot. It will look like a lot at first, but it wilts quickly, releasing its vibrant green color and earthy scent.
Cover the crockpot and set it to low. Let it cook for about 4 hours; during this time, the greens will soften and the flavors will meld into a fragrant, earthy aroma that fills your home.
Once the cooking time is up, open the lid and use an immersion blender to blend the soup directly in the crockpot until smooth and velvety. If you prefer, transfer the soup in batches to a blender and purée until silky.
Stir in a squeeze of lemon juice and taste the soup. Adjust seasoning with salt and pepper, and add a pinch of nutmeg if using. The soup should have a bright, vibrant green color and a silky consistency.
Let the soup rest uncovered for about 10 minutes, allowing the flavors to settle and the texture to thicken slightly. Then, ladle into bowls and enjoy while warm, garnished with a drizzle of olive oil or a sprinkle of fresh herbs if desired.
