Chicken that actually fits on a sandwich

RECIPE, MAKES 2 SANDWICHES

• 1 large chicken breasts
• 2 soft buns (I like brioche for this)
• lettuce
• tomato
• garlic (I do one clove per sandwich)
• oil (I like olive oil but it's strong)
• mustard (I like dijon for this)
• dill pickles
• butter
• salt
• salt
• pepper
• American cheese (IF you want to do the melt version I show at the end of the video)

1. Cut the chicken breast in two about 2/3rds of the way up from the skinny tail end. Butterfly both pieces. For a quick 30-60 min brine, dissolve 15g of salt (1 tablespoon of my kosher salt) in one cup (240mL) of cool water, along with an equal quantity of sugar. If you want to brine the chicken longer, like overnight, I'd cut the salt in half. Don't worry if the salt doesn't all dissolve immediately. Submerge the chicken and let brine.
2. To make the aioli, peel and chop the garlic as fine as you can. Sprinkle on some salt and use the side of your knife to grind the garlic down to a paste. Put the paste in a small bowl, along with a roughly equal quantity of mustard. Stir in oil, a little bit at a time, to form an emulsion. Put in as much oil as the garlic and mustard with emulsify. Watch the video to see how. This sauce will be very strong at first, but will mellow out in time. Make it the day before if you don't like the heat of raw garlic.
3. Prepare a weight for flattening the chicken as it cooks — I wrap a brick in aluminum foil.
4. Remove the chicken from the brine and pat it dry. Season it with pepper and anything else you want, but no additional salt. Heat a pan until butter foams in it. Melt a thick film of butter into the pan, place in the chicken and smash down with the weight. Cook until the bottom is lightly golden brown and the chicken seems at least halfway cooked through — 2-3 minutes. Flip the pieces and cover again with the weight. A thermometer isn't much use on something so thin, so I'd just cook it another couple minutes until the inside feels bouncy when you poke it, rather than squishy, and everything looks cooked from the outside. Give it one more quick final flip to kill surface bacteria, because the side you cooked first just touched the brick, which previously touched raw chicken. Take the pieces out to a plate or something — the interior will continue to cook as they rest.
5. Toast the cut sides of the bun in the pan if you want. Let the bread and the chicken cool for about 5 minutes before dressing the sandwich, because the emulsion of the aioli will break if you get it hot. I do bottom bun, lettuce, tomato, chicken, aioli, pickles, top bun — but you do you.
6. If you want, you can make a grilled sandwich by placing cheese around the chicken, returning the sandwich to the pan with plenty of melted butter in there, press with the weight until brown on the bottom, flip, repeat, flip again one time (because the brick touched the raw chicken).