Preheat the oven to 350°. Spread the pecans on a rimmed baking sheet and bake for 12 minutes, or until browned and fragrant. Let cool, then coarsely chop the pecans.
In a medium saucepan, combine the sugar and water and cook over moderate heat without stirring, until a deep amber caramel forms, about 20 minutes. Gradually stir in the heavy cream and continue stirring to dissolve any lumps of caramel, about 2 minutes. Remove from the heat and stir in the bourbon and the pecans. Serve the sauce warm or at room temperature.
The sauce can be refrigerated for up to 3 days. Bring to room temperature or rewarm gently before serving.