First, combine the heavy cream, broth, bay leaf, salt, and pepper in a medium saucepan. Add the peeled pearl onions to the liquid. Bring the mixture to a simmer over medium-high heat, then immediately lower the heat to maintain a gentle simmer.
Let the onions cook for about 20 to 25 minutes. During this time, the onions will become tender and absorb the flavors of the sauce. The liquid will also reduce and thicken slightly, creating a light cream sauce that perfectly coats each onion.
Once the onions are tender, remove the pan from the heat and discard the bay leaf. If you're using Parmesan, stir it in now until it melts into the sauce. Finally, stir in the freshly minced parsley and transfer the creamed onions to a serving bowl. Serve them hot.