Pick over the split peas and discard any misshapen peas or stones.
In a saucepan over medium heat, melt the butter.
Add the onion and
sauté, stirring occasionally, until tender and translucent, about 10
Add the split peas, carrots, bay leaf, and 6 cups stock.
Raise the heat to high and bring to a boil.
Cover, reduce the heat to
low, and simmer until the peas are very soft, 45 minutes.
mixture seems too thick, add more water or stock as needed.
Discard the bay leaf.
Add the spinach and simmer until it wilts,
about 3 minutes.
Meanwhile, if using the bacon or pancetta, place a frying pan over
Add the bacon or pancetta slices and dry, turning as
needed, until crisp, about 7 minutes.
Transfer to paper towels to
When cool, crumble.
Remove the soup from the heat and let cool slightly.
batches, puree in a blender or food processor.
Return to a clean
saucepan and add milk, water, or stock as needed to thin to desired
Place over medium-high heat and reheat to serving
Season with the salt and pepper.
To serve, ladle into warmed bowls and sprinkle with the crumbled bacon
or pancetta, if using.