Chop chocolate and set aside in a heat proof bowl. In a pot, bring milk and cream to a simmer. While the milk and cream is heating through, whisk together the eggs and sugar until light yellow in colour.
Once the milk and cream has come to a simmer, slowly stream the hot milk mixture into the egg and sugar mixture, whisking constantly. Pour this back into the pot and heat on low stirring constantly so the eggs don't over cook.
You'll know when the custard is finished when it coats the back of a spoon. Pour the warm custard over the chopped chocolate and let sit for a few minutes. Whisk until smooth. Add in a pinch of salt, whisk and then cover so the crémeux doesn't form a skin. Refrigerate until set.