Preheat oven to 350°F. Spread nuts on a baking sheet and toast in the oven, stirring a few times, for 10 to 15 minutes, until hazelnuts are browned.
While nuts are roasting, warm milks, honey, and salt in a small saucepan over medium heat until it just starts to boil. Remove from heat. In a bowl set over a pan of barely simmering water, melt chocolates together until smooth.
Once hazelnuts are well-toasted, immediately place warm nuts in a clean tea towel. Rub the towel vigorously with your hands to remove any loose skins. They don’t need to be pristine; just try to get as much off as possible. In a food processor, grind warm hazelnuts as fine as possible. You may not be able to get them completely smooth. Add melted chocolate, and continue to process the mixture, stopping to scrape down the sides of the work bowl as necessary. Once the mixture is smooth, add the warm milk mixture and sea salt. Process until well combined. Store, covered, in the refrigerator.