Bring a large pot of salted water to a boil and add the spaghetti, cooking until al dente according to package directions. While the pasta cooks, prepare your mise en place: mince the shallot finely, mince the garlic cloves, and finely chop the parsley. Once the pasta is done, drain it while reserving 1 cup of pasta water—this starchy water is essential for tossing the pasta with the sauce later. Set the cooked pasta aside.

Pat the chicken cutlets dry with paper towels—this helps them brown better. Season both sides generously with salt and black pepper, then lightly coat each cutlet in flour, shaking off any excess. I like to season the flour with a pinch of salt and pepper before dredging; it helps build flavor from the first sear.

Heat olive oil in a large skillet over medium-high heat until shimmering. Working in batches if needed to avoid crowding the pan, add the floured chicken cutlets and cook for 3-4 minutes per side until golden brown. Transfer the seared chicken to a plate and set aside. Do not wash the skillet—the browned bits on the bottom (called fond) are pure flavor that will build your sauce.

Reduce heat to medium and add 3 tablespoons of butter to the same skillet. Once melted, add the minced shallot and cook for about 1 minute until fragrant, then add the minced garlic and cook for another 30 seconds. Add the capers and pour in the white wine, using a wooden spoon to scrape up all the flavorful fond from the bottom of the pan. Let the wine reduce slightly for about 1 minute, concentrating the flavors.

Stir in the chicken broth, lemon juice, and lemon slices. Season with salt, black pepper, and red pepper flakes to taste. Return the seared chicken cutlets to the skillet and simmer gently for 2-3 minutes until the chicken is cooked through. Remove the chicken and set aside on a clean plate, leaving the sauce in the skillet.

Turn off the heat and whisk in the 4 tablespoons of butter to the sauce, stirring until it melts and creates a silky, cohesive sauce. I find that finishing with cold butter gives the sauce a luxurious sheen that makes this dish feel restaurant-quality. Add the cooked pasta directly to the skillet with the sauce, tossing gently and adding pasta water a little at a time until the pasta is well-coated and moves freely—you want a light sauce that clings to each strand, not a heavy pool of liquid.

Divide the sauced pasta among serving plates or bowls. Top each portion with a seared chicken cutlet and drizzle with any remaining sauce from the skillet. Finish with a generous sprinkle of fresh chopped parsley and a light grind of black pepper.