Make the dressing: In a medium bowl, whisk the vinegar, olive oil, mascarpone, walnut oil, salt and pepper. Using a rubber spatula, fold in the crumbled gorgonzola. Let the dressing sit at room temperature for 10 minutes to let the flavors mingle, or refrigerate until ready to use.
Make the salad: In a large bowl, combine the radicchio, endive, kale, dates and toasted walnuts. Add the dressing and toss gently until evenly coated. Ribbon the prosciutto on a serving platter and mound the salad on top. Top with shaved gorgonzola.
To make shaving the gorgonzola easier, freeze a piece of the cheese for at least 2 hours, then use a vegetable peeler to shave some over the salad.
Photograph by Linda Xiao