Heat olive oil in a large soup pot over medium-high heat.
Add the chopped onions, salt, black pepper, and red pepper flakes.
Cook while stirring for about 2 minutes.
Include the chopped garlic and bay leaf into the pot.
Cook for another minute, maintaining gentle stirring to prevent sticking.
Add the rinsed split peas and chicken broth to the pot.
Bring the mixture to a boil, then lower the heat to a medium setting.
Allow the soup to cook, stirring occasionally, for about 1 hour or until the peas are tender.
If the soup begins to thicken too much, add a little more broth or water to reach your desired consistency.
Once the peas are tender, remove the bay leaf.
Taste and adjust seasoning with more salt and pepper if needed.