Using a vegetable peeler, remove the zest from 1 of the oranges, being careful to avoid the white pith. Juice the oranges to get approximately ½ cup juice.
Put the zest in a food processor fitted with the steel blade. And pulse to mince.
Add the sugar and pulse again until the zest and sugar are mixed together.
Add the butter and pulse to combine. Add the eggs, 1 at a time
Pour the mixture into a medium saucepan and stir in the blood orange juice.
Cook over low heat until thickened, about 10 minutes, stirring constantly.