Shape the goat cheese into eight 1-in.-thick disks and put in a container just big enough to hold them in one layer. Sprinkle cheese with herbs and pour on olive oil. Cover and chill at least 12 hours and up to a week (see Notes). One hour before baking, pop them in the freezer to firm up.
Preheat oven to 400°. Remove cheese from marinade and roll all sides in panko, pressing gently so the crumbs adhere. Arrange on a large baking sheet and bake until golden, about 15 minutes, turning over halfway through. Add baguette slices for last 5 minutes of baking.
Whisk together vinegar, salt, pepper, and walnut oil. Put lettuces in a large bowl, drizzle with just enough dressing to coat, and toss gently and thoroughly.
Divide lettuces among 4 plates, sprinkle with walnuts, and to each plate add 2 goat-cheese disks and a baguette slice. Serve immediately.
Note: Nutritional analysis is per serving.