Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper. Set the slices of focaccia on the baking sheet.
Bake 6 to 8 minutes, or until lightly toasted. Remove from the oven and set aside. Combine the mayonnaise, buttermilk, sugar, lemon juice, garlic, parmesan cheese, pepper, Tabasco and Worcestershire sauce in a small bowl. Divide the lettuce among 4 salad bowls. Drizzle some of the dressing over top and serve the rest tableside. Garnish the salad with the croutons, lemon wedges and, if desired, some additional freshly grated parmesan cheese.