How to Make It
Whisk eggs in a medium saucepan until thoroughly blended. Whisk in broth. Place saucepan over low heat; cook, whisking gently and constantly and scraping bottom of pan so as not to incorporate any air (you should not see any bubbles on sides of pan), until eggs begin to thicken, form fine curds, and have the texture of loose polenta, 5 to 6 minutes. Quickly whisk in crème fraîche and salt until blended. Immediately remove from heat, and, using a large spoon or rubber spatula, stir in butter until melted. Stir in truffles, if using; chives; and salt to taste.
Spoon eggs into warmed bowls, and drape with ham slices. Serve immediately with toasted brioche slices.