Marinate chicken breasts in 1 cup of coffee syrup for several hours or overnight. Preheat a grill or broiler. In a saucepan combine remaining 1 tablespoon coffee syrup with remaining ingredients, except cream, and bring to a boil. Reduce heat and simmer 30 minutes. puree with an immersion blender and pass sauce through a strainer into a clean saucepan. Or pour sauce into a blender or food processor and puree; strain for a very smooth sauce. Whisk in cream and adjust seasonings to taste. Meanwhile, grill or broil chicken, turning once, until well-browned, about 8 minutes in all. To serve, top each chicken breast with sauce and garnish with pistachios and cilantro leaves.