In a small enamel-coated cast-iron Dutch oven, stir together sugar and 3 tablespoons water until moistened. Cook over medium-high heat, gently swirling pan but not stirring, until mixture is light golden brown; using a pastry brush, brush down sides of pan with remaining 1 tablespoon water to prevent sugar from crystallizing.
Remove from heat; carefully whisk in cream and coconut milk until smooth and well combined. (Mixture will bubble up.) Whisk in butter until melted and well combined; whisk in rum. Pour into a heatproof bowl, and let cool completely before using.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/grilled-tropical-fruit-skewers/