Combine chocolate, cream cheese and double cream in a saucepan over medium heat; cook and stir until chocolate is melted and mixture is smooth, about 5 minutes. Remove from heat and stir in 1 tablespoon cinnamon, vanilla extract and nutmeg.
Pour chocolate mixture into a small bowl and refrigerate until firm but still pliable, 1 1/2 to 2 hours.
Combine remaining 1 tablespoon cinnamon and walnuts in a shallow bowl.
Roll chocolate mixture into balls and set on a plate. Sprinkle walnuts on top, pressing walnuts to make sure they stick. Refrigerate truffles until fully firm, 8 hours to overnight.