3 Seville oranges, juice and zest
2 Meyer lemons, juice and zest
4 eggs, beaten
12 oz coconut or cane sugar
8 Tbsp unsalted butter (2 sticks), softened and cut into cubes

In a saucepan combine all ingredients over low heat and whisk. Continue whisking until the mixture thickens, about 10 minutes. Remove from heat and pour into sterilized jars.