Savory Palmiers with Bacon, Swiss, and Caramelized Onions

1. Lay one sheet of puff pastry on a lightly-floured surface. The dough should be about 1/8-inch thick; if needed, roll it out slightly.
2. Spread the dough with 1 tablespoon of cream-style horseradish. Distribute the remaining ingredients across the pastry, in the following order: 1 cup Gruyère, 1/3 cup caramelized onions, half of the crumbled bacon, 1/2 teaspoon chopped fresh thyme. Place a piece of plastic wrap or parchment paper on top of the pastry and press down gently to compact layers (or, gently roll over it with a rolling pin).
3. Starting at one of the long sides, tuck and roll the pastry until you reach the center of the sheet. Roll the opposite end toward the center until the two rolls meet. Dab a few drops of water onto the pastry if the rolls don't stick together in the center.
4. Repeat process with second sheet of puff pastry and remaining ingredients.
5. Wrap the pastry rolls in plastic wrap and refrigerate at least 1 hour, or freeze 30 minutes, until firm (but not completely frozen). Unwrap and cut with a sharp knife into 1/4-inch thick slices, about 24 per roll.

To bake immediately:

1. Preheat oven to 400 degrees F. Line two baking sheets with parchment paper. Place sliced palmiers 1-inch apart on the baking sheets.
2. Bake until golden and flaky, 12-15 minutes, rotating pans halfway through. (Bake time will depend on how cold your pastry is before going into the oven.)
3. Let rest 2-3 minutes and loosen palmiers from parchment with a thin metal spatula. Transfer to a wire rack to cool slightly. Serve warm.

To freeze and bake later:

1. Freeze palmiers on baking sheets until solid, then transfer to freezer-safe bags for storage, up to 1 month.
2. Preheat oven to 400 degrees F. Place frozen palmiers 1-inch apart on parchment-lined baking sheets. Bake, from frozen, 15-18 minutes, until golden and flaky, rotating pans halfway through. Continue as directed above.