With a whisk, mix together the cream, sugar and egg yolks in the top of a double boiler off the heat. Add the butter and heat the mixture over boiling water. Once the butter has melted, cook for 10 minutes, whisking occasionally, until slightly thickened.
Remove from the heat and pour the mixture into a medium mixing bowl. Whisk in the vanilla. Let cool completely, stirring occasionally, about 2 hours.
When the sugar-egg mixture is cool, stir in the coconut and pecans. Let sit for 15 minutes.
Use as directed or store tightly covered in the refrigerator for up to 1 week. If refrigerated, let come to room temperature and stir to remix before using.