For the guava bread pudding: Preheat the oven to 350 degrees F. Grease a loaf pan with the butter.
In a large bowl, combine the brioche, 1/2 cup of the brown sugar, and the white sugar, allspice, cinnamon, nutmeg, milk, eggs, golden raisins and guava paste. Mix well. Transfer to the prepared baking pan.
Bake until brown on top, about 45 minutes. Cool on a rack.
For the marshmallow-vanilla cream sauce: Meanwhile, melt the marshmallows in a nonstick skillet over low heat. Add the heavy cream, confectioners' sugar and vanilla. Continue to cook over low heat, stirring, until the sauce comes together.
To serve, invert the bread pudding onto plate and spoon some sauce over the top.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.