Prep the chicken and potatoes: Pat the chicken breasts dry with paper towels (drying ensures a better sear because moisture prevents browning). Season both sides of the chicken with 3/4 teaspoon kosher salt, 1/4 teaspoon black pepper, and 1/2 teaspoon smoked paprika. Cut larger chicken breasts in half horizontally if they’re uneven so they’re an even thickness; even thickness cooks evenly and prevents dry edges.

Parboil the potatoes: Place the potatoes (whole if small, halved if medium/large) in cold, salted water (about 1 tablespoon salt per 2 liters) and bring to a simmer. Parboiling for 10–12 minutes (until just tender when pierced with a knife) cooks them through while preserving structure so they’ll smash without falling apart — this step lets you get maximum crispiness when pan-frying later. Drain and let steam-dry for a minute.

Smash the potatoes: On a sheet tray or cutting board, use the bottom of a glass or a potato masher to gently press each potato until about 1/2-inch thick. The goal is to increase surface area so the potatoes crisp quickly; don’t pulverize them — maintain some texture.

Start the potatoes crisping: Heat 1 tablespoon olive oil and 1 tablespoon butter in a large heavy skillet over medium-high heat (cast iron preferred for even browning). Add the smashed potatoes in a single layer — don’t overcrowd the pan (work in batches if necessary). Let them cook undisturbed for 3–4 minutes so a golden crust forms; flipping too soon prevents proper browning.

Flip and finish the potatoes: Turn potatoes and add a pinch more salt, the dried thyme, and 1/4 teaspoon smoked paprika. Cook another 2–3 minutes until both sides are golden and edge-crisp. Transfer to a warm plate and loosely tent with foil to keep warm while you cook the chicken. Cooking the potatoes first creates fond (browned bits) in the pan that will boost the pan jus flavor.

Sear the chicken: Pat the skillet dry, add remaining 1 tablespoon olive oil, and heat over medium-high until shimmering. Add the chicken breasts, presentation-side down if you butterflied them. Sear without moving for 3–4 minutes until a deep golden crust forms — this Maillard reaction creates savory, complex flavors and locks in juices.

Flip and finish in the oven (or pan): Flip the chicken and add 1 tablespoon butter to the skillet, spooning a little melted butter over the top for flavor and to help even cooking. If breasts are thicker than 1 inch, transfer the skillet to a preheated 375°F (190°C) oven for 6–8 minutes until internal temperature reads 155–160°F (68–71°C). Residual carryover heat will bring it to the safe 165°F while keeping meat juicy. If breasts are thin, finish on the stovetop over medium heat, covered, for 4–6 minutes, checking temperature.

Rest the chicken: Transfer the chicken to a cutting board and tent loosely with foil for 6–8 minutes. Resting lets the juices redistribute; slicing immediately causes juices to run out and dry meat.

Make the lemon-garlic pan jus: With the skillet still hot, reduce heat to medium and add the chopped onion. Sauté 2–3 minutes to soften and release sweetness (this balances the lemon). Add the minced garlic and sauté for 20–30 seconds until fragrant — don’t brown it or it turns bitter. Add lemon zest and lemon juice to deglaze the pan, scraping up browned bits (fond). Add any accumulated resting juices from the chicken carving board. Swirl in 1 tablespoon butter off the heat to emulsify the sauce — butter mellows acidity and gives a glossy finish.

Finish and plate: Slice the rested chicken on a slight bias. Arrange a bed of crispy crushed potatoes on each plate, place chicken slices over the potatoes, and spoon lemon-garlic pan jus over the chicken. Sprinkle chopped parsley and an extra pinch of flaky salt for brightness and texture.

Serve hot and enjoy: Serve immediately so potatoes stay crisp and chicken is warm. The combination of textures — crisp potato, tender chicken, and silky pan jus — is what elevates this dish to restaurant caliber.