Served hot and filled with goodies, sandwiches easily make the move from lunch pail to dinner table.

We tend to relegate certain foods to particular times of the day-eggs for breakfast, sandwiches for lunch, pasta for supper. But we all know deep in our hearts that pancakes and eggs sometimes make a great supper, and that more than one among us has happily started the day with a plate of reheated spaghetti. For example, a grilled Turkey and Cheese Panini―crunchy on the outside and oozing with cheese on the inside―will satisfy even the hungriest of appetites.

These 20 hearty sandwiches are knife-and-fork foods―more substantial than their handheld lunchtime cousins. And should be served these warm, rather than cold or at room temperature. If that sounds odd, it's actually very traditional. In older American cookbooks, developed for a time when people often hosted luncheons, there was always a section featuring these heartier sandwiches: creamed chipped beef on toast or Welsh rarebit. Easy and economical when meat wasn't available, they were also quite suitable for a family supper.

The form is flexible, too―from open-faced Onion-Smothered Chicken Sandwiches to meatless Eggplant-and-Portobello Mushroom Melts. Feel free to mix and match breads, cheese, and fillings to create your own signature sandwich. You're limited only by your imagination.