2 packages (6 flatbreads each) Flatout Foldit Sweet Hawaiian Flatbreads (see note)
Preheat oven to 350°F.
Cut all 12 of the Flatout Foldits in half longways (refer to photos in post if needed), to yield 24 halves. Set aside.
In three small, separate bowls, combine the "Buttery Spread" ingredients (butter through Worcestershire sauce) for each type of sandwich. Whisk or stir to combine thoroughly (but note in the post's photos that the Buttery Spreads will still look a bit lumpy from the onions and from bits of butter). Set aside.
To assemble sandwiches, lay halved flatbreads out on a work surface, working in batches to assemble each sandwich type. (Refer to step-by-step photos in the post if needed.) For each of the three sandwich types:
1) Evenly slather 8 flatbread halves with 3 tablespoons of the Buttery Spread (reserving about 1 tablespoon).
2) Top with cheese, dividing the cheese evenly among all 8 flatbread halves.
3) Next, top with meat, dividing evenly.
4) Roll each of the 8 sandwiches into a spiral and place it, cut side down, into an ungreased 11x7-inch baking dish, tucking in edges so spirals stay closed during baking.
5) Using a pastry brush or rubber spreader, dab the reserved 1 tablespoon of the Buttery Spread evenly across the top edges of the 8 sandwiches.
Repeat this process with the next two types of sandwiches, beginning with slathering the Buttery Spread on the flatbreads, then adding cheese, then adding meat, then rolling up and dabbing the tops with a little more of the Buttery Spread.
Once all 24 rolled sandwiches are placed in the pan, cover pan with foil and bake for about 30 minutes, until the sandwiches are warmed through and the cheese is slightly melty but not runny. (Alternately, you can delay baking by several hours or up to 1 day, refrigerating the pan of finished sandwiches, covered, until you're ready to bake them. See note below about make-ahead options.)
Flatbreads: If your store doesn't carry the Sweet Hawaiian variety of Foldit flatbreads, feel free to experiment with mixing and matching other Foldit varieties. We've also tested this recipe with the 5 Grain Flax and the Ancient Grains varieties. Both are delicious with this recipe, and both are loaded with protein, fiber and whole grains. Note, however, that some varieties have 5 flatbreads per package, while others have 6. You will need a total of 12 flatbreads to yield the 24 sandwiches in this recipe.
Grating onion: As shown in the photo in the post above, we recommend grating the onion on the medium-sized grater side of a box grater.
Choosing meats: We recommend selecting natural and minimally processed lunch meats, and also choosing leaner varieties whenever possible.
Swapping meats, cheeses and spreads: As mentioned in the post, feel free to experiment with different combinations of flavors, or even to fill an entire pan with all one type of sandwich if you have a favorite.
Make-ahead options: You can completely prepare these spiral slider sandwiches prior to baking, up to a day in advance, which is great for parties and entertaining. Simply cover the baking pan and refrigerate until baking.
In addition, after baking, these are great for quick, grab-and-go snacks and mini meals throughout the week. You can bake the entire pan, then cool and refrigerate until needed. After being baked, the sandwiches can be eaten cold, but are even more delicious rewarmed gently in the microwave, for about 10-15 seconds each.