Babas au Rhum with Mixed Citrus Fruits

Name: Babas au Rhum with Mixed Citrus Fruits
Ingredients: 2 tablespoons milk; 1 tablespoon plus 1/2 teaspoon sugar; 1/2 teaspoon fine sea salt; 1/2 vanilla bean, split lengthwise, seeds scraped; 1 teaspoon active dry yeast; 3/4 cup plus 2 tablespoons all-purpose flour; 2 large eggs; 4 tablespoons unsalted butter at room temperature, cut into 1/2-inch cubes, plus more for greasing; 2 cups water; 1 cup sugar; 1/2 cup dark rum; 1 ruby red grapefruit; 1 blood orange; 1 navel orange; 1/2 cup heavy cream, chilled; 1 1/2 teaspoons sugar; 1/4 teaspoon pure vanilla extract; Thinly sliced lime wheels and grapefruit zest, for garnish (optional)