This is published in the October 2004 Bon Appetit as open-faced sandwiches, but I make this as a 12-inch pizza (a big, round, open-faced sandwich?). I wasn't sure whether we would like the sweetness of the apple butter, but there is enough savory/salty flavor in the rest of the recipe that it works well (I probably used more Dijon, though, and less apple butter, than called for in the recipe). In pizza format, it is good with some sauteed onion and some very well wrung out thawed frozen spinach added. I think this is a recipe that depends a lot on the types of ingredients used; since it has the apple butter, sweeter mustards and milder cheeses would probably not be as good. The relative proportions of Dijon and apple butter (and meat and cheese) can be adjusted for personal taste.