In a bowl, beat the eggs with granulated sugar and vanilla. Add the milk and mix.
Pour the mixture into a saucepan and heat over low heat or in a double boiler, stirring constantly, until thickened. Do not boil or overheat!!!
Let it cool.
Softened butter is whipped with a mixer into a fluffy white mass.
While continuing to beat, gradually add the egg-milk mixture in small portions. Before finishing the beating, add cognac or rum – as desired. The result should be an airy and smooth cream.
Use the cream as intended immediately. But you can store it in a closed container in the refrigerator for no more than 3-4 days.