Step 1

Melt the butter in a large pot over medium-high heat. Add the onion and garlic and cook until the onion is transparent, about 3 minutes.

Step 2

Add the peas, spinach, stock, and thyme and bring nearly to a simmer. (If you are using fresh peas, simmer for 5 minutes.)

Step 3

Blend the soup with an immersion blender or in 2 batches in a regular blender. Return the soup to the heat and warm through. If using, add the yogurt then season to taste with salt.