In a large bowl, dissolve the yeast with the milk. Allow it to proof in a warm place for 10 minutes. Mix in the flour and eggs, beating well until dough is smooth. Cover the bowl, and let rise at room temperature for 45 minutes.
Preheat the oven to 350 degrees F. Brush 6 individual savarin molds or ramekins with butter.
Mix 5 tablespoons softened butter, the salt, and sugar into the dough, slapping it against the sides of the bowl. Fill molds almost full with the dough. Let the dough rise until molds are full. Bake for 20 to 25 minutes, until golden brown and a small knife or wooden skewer can be inserted in cake and removed cleanly.
To make the syrup: Combine the sugar and water in a saucepan over high heat. Bring to a boil, stirring to dissolve the sugar. Remove from heat and cool until lukewarm. Add the vanilla and rum.
Brush the cakes with the syrup, let it soak in, then brush again. Repeat until all the syrup is used or the cakes will absorb no more syrup. Place the soaked cakes on individual plates. Garnish with Blood Orange Marmalade and whipped mascarpone.
Slice the fruit very thin on a slicer or with a very sharp blade, removing all seeds as you go.
You should have approximately 2 1/2 pounds of fruit. For every pound of fruit add 2 pints of water in a large heavy bottomed pot. Add the vanilla beans and cinnamon. Bring to a boil and cook until the fruit skin is tender, approximately 10 minutes. Remove from heat, cool and refrigerate overnight.
Weigh the fruit and water mixture. You should have approximately 5 pounds. For each pound of fruit and water, add 1 pound of sugar. Bring to a boil and then continue to cook over medium heat, stirring frequently. To test, drip a small amount of the syrup onto a cool plate. When it's the consistency of honey at room temperature, it is ready (about 1 hour or more). Remove from heat and allow to cool. Leftover marmalade will keep in the refrigerator for several weeks.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.