Mexican Eggnog (Rompope)

2 cups granulated sugar
8 egg yolks
2/3 cup whipping cream
1 teaspoon vanilla extract
1 (14 ounce) can sweetened condensed milk
2 cups light or dark rum
2/3 cup bourbon

Beat sugar and egg yolks together until well combined, then beat in the remaining ingredients, one at a time, until the sugar is dissolved. Store, refrigerated, in a glass jar for no more than a few days.