Step 1: Sauté Onions : In a large pot, heat olive oil or butter over medium heat. Add chopped onions and cook until translucent, about 5 minutes.
Step 2: Add Garlic : Add minced garlic to the onions and sauté for 1–2 minutes until fragrant, being careful not to burn the garlic.
Step 3: Cook Spinach : Add the chopped spinach to the pot. Cook for 2–3 minutes until wilted, stirring occasionally.
Step 4: Add Broth and Simmer : Pour in the vegetable or chicken broth and bring the mixture to a gentle simmer for 5–7 minutes to allow flavors to combine.
Step 5: Blend the Soup : Use an immersion blender to puree the soup directly in the pot until smooth. Alternatively, blend in batches in a standard blender.
Step 6: Add Cream and Season : Stir in milk or cream and gently heat without boiling. Season with salt, pepper, and a pinch of nutmeg if desired.
Step 7: Serve : Ladle soup into bowls and garnish with grated Parmesan cheese or a drizzle of olive oil. Serve warm.