In a pan, gently toast the pecans on low to medium heat till they darken slightly and a warm all through. Remove from heat and add 1 teaspoon dulce de leche to the nuts in the pan, stirring to ensure they are coated. Remove onto a plate or rack and allow cool down. Once cold, chop into small pieces.
In a small bowl, combine the butter, remaining teaspoon of dulce de leche, the horseradish (to taste) and then check for seasoning and balance. Season accordingly with the salt and fold in the caramelised pecans. Refrigerate till ready to use