Pat the chicken breasts dry with paper towels. If thick, slice each breast horizontally to make two cutlets or place between plastic and gently pound to even thickness about 1/2 inch. Season both sides evenly with 1 1/2 tsp kosher salt and 1 tsp black pepper.

Dredge

Spread 1/2 cup all-purpose flour on a plate and lightly dredge each seasoned breast, shaking off excess flour.

Sear

Heat 2 tbs olive oil and 1 tbs unsalted butter in a large skillet over medium-high heat until shimmering. Add chicken in a single layer (work in batches if needed). Cook 3-4 minutes per side, until golden brown and just cooked through (internal temperature 160-165°F / 71-74°C). Transfer cooked chicken to a warm plate and tent with foil.

Lemon Sauce

Sauté aromatics

Reduce heat to medium. In the same skillet, add remaining 1 tbs butter. Add 1/2 sliced yellow onion and sauté 3-4 minutes until softened. Add 3 minced garlic cloves and cook 30-45 seconds until fragrant, stirring to avoid burning.

Deglaze and combine

Pour in 1 cup chicken broth, scraping up browned bits from the bottom of the pan with a wooden spoon. Stir in 1/2 cup fresh lemon juice, 1 tbs lemon zest, 1 tbs honey, and 1 tsp Dijon mustard. Bring mixture to a gentle simmer.

Thicken sauce

Whisk 1 tbs cornstarch with 2 tbs cold water until smooth to make a slurry. Slowly whisk the slurry into the simmering sauce. Continue simmering 1-2 minutes until sauce thickens slightly and coats the back of a spoon. Taste and adjust seasoning with a pinch more salt or honey if too tart.

Finish

Return the seared chicken and any accumulated juices back to the skillet, spooning sauce over the breasts. Simmer gently 2-3 minutes to allow flavors to meld and chicken to reach final safe temperature (165°F / 74°C). Stir in 2 tbs chopped fresh parsley just before removing from heat. Garnish with lemon slices if desired.

To Serve

Serve the lemon chicken over cooked rice or pasta, spooning extra lemon sauce over the top. Sprinkle additional chopped parsley and a little lemon zest if desired.