In a heavy stockpot, over medium heat, heat the olive oil. Saute the onions with the salt and pepper until translucent, 5 to 7 minutes. Add the garlic, tomatillo and jalapeno(s) and cook another 5 minutes. Pour in the chicken stock or water. Bring to a boil, reduce to a simmer and cook 20 minutes. Stir in the lettuce and cook 10 minutes longer. Add the cilantro to the soup and bring to a boil. Remove from the heat, and puree in a blender or food processor. If you want a more elegant soup, pass through a strainer. Bring back to a boil before serving. Beat 1 cup of the heavy cream until soft peaks form. In a small bowl, mix the anchovy paste with the remaining 2 tablespoons cream until smooth. Fold into the whipped cream and beat a few more strokes. Serve the soup hot with dollops of the anchovy cream garnish.