In a saucepan, bring the cream and vanilla bean and seeds to a simmer over medium heat. Remove the pan from the heat and remove the vanilla bean. Add the chocolate and whisk until smooth. Mix in the Nocello. Cool completely, stirring occasionally, usually about 30 minutes. Chill the mixture, covered, until firm, usually 2 to 3 hours.

Line a baking sheet with waxed paper and place the chopped, toasted nuts in a medium bowl or baking dish. Using a melon baller, scoop out the truffle mixture to form 1-inch round balls. Roll lightly in your hands if necessary to shape, then roll in the nuts, pressing lightly so that nuts adhere to the truffle. Place truffles on prepared baking sheet, cover and chill until firm, about 2 hours.