Add heavy cream to a measuring cup and pour in milk. Add to a saucepan and add sugar and vanilla seeds. Whisk and bring to a boil.
In the meantime, whisk egg yolks in a bowl. When milk-mixture starts to boil, add to egg yolks while whisking vigorously.
Add mixture back into saucepan and reheat over medium heat. Whisk constantly until sauce is thick and creamy. Enjoy with a variety of desserts!