Wash one of the blood oranges very well. Use a zester or microplane to zest the peel to total 1 teaspoon. Cut that orange in half and juice it into a juicer that strains the pulp. Add the juice, about five tablespoons, to a small heavy saucepan. Add the powdered sugar and zest and heat over low heat, stirring until the sugar dissolves. Turn the heat up to medium and bring to a boil, stirring fairly constantly, until sauce is syrupy and reduced by half, about five minutes. Pour into a ramekin and set aside to cool. If syrup is too thick when youre ready to use it, stir in a little hot water.

Carefully peel and separate the segments of the two remaining oranges. Set aside.

Break up the chocolate bar into a microwave safe bowl I halve each triangle. Microwave on high and stir every 30 seconds, until melted, about 75 seconds total.

Scoop cup of ice cream into four ice cream cups. Spoon two scant teaspoons of blood orange syrup over the ice cream. Arrange orange segments around the ice cream, along the edges of the bowl and drizzle segments with about 2 tablespoons melted chocolate. Serve immediately.