Mix the egg yolk and mustard in a bowl and spread the mixture evenly over the ham. Sprinkle with the bread crumbs and crushed gingersnaps.
Heat the oven to 475 F (250 C) or make it golden brown with a kitchen blowtorch. (The breadcrumbs should become golden brown.) If you use the oven, 5 to 10 minutes should be enough.
Serve the ham at room temperature with sautéed cabbage and mustard.