Cut the chicken thighs into bite-size pieces and place them on a sheet tray in a single layer. Transfer to the freezer and freeze for 1 hour, or until the chicken pieces are quite hard but sliceable.

Working in batches, fill the bowl of a food processor with a single layer of the chicken. Pulse until the chicken is coarsely ground. Remove the ground chicken to a bowl and repeat until all the chicken is ground.

Cut 11 pieces of parchment paper into a 6-inch square. Arrange them on a work surface, then place a 3-inch-round cookie cutter on one sheet. Fill the cutter with ground chicken to about ¾-inch high, remove the cutter, then press the patty down with a flat-bottomed plate until it’s about ¼-inch-thick and flat on top. Repeat with the rest of the chicken.

Place the patties (keeping the parchment underneath) in a single layer on a sheet pan, then place in the freezer for 2 hours.

In a small bowl, mix together the salt, black pepper, and white pepper. Season the patties on one side.

Spread the cut sides of each bun with ½ tablespoon butter per side. In a large skillet over medium-high, toast the buns cut sides down until golden brown. Transfer to serving plates, then spread one side of the bun generously with mayonnaise and the other side with Dijon mustard.

Heat the skillet over high heat with just enough canola oil to coat the skillet plus ½ tablespoon butter per patty. When the butter’s foaming, place the patties in the skillet seasoned side down and remove the other piece of parchment, then season the second side.

Use a flat spatula to gently press down on the patties against the skillet. Cook, without moving the patties but continuing to press down on the center, until the first side is deeply browned.

Carefully flip the patties and allow the second side to crisp up and brown and the interior to cook through.

Place the crispy patty on each bun. Place a slice or two of cheese on each burger, then serve immediately with pickles.