Place chicken breasts between two sheets of plastic wrap or parchment paper. Using a meat mallet, pound to an even ¾-inch thickness. Pat dry with paper towels. Season with ½ tsp salt and black pepper on both sides.

Heat a heavy skillet over medium-high heat until it reaches 375°F (190°C). Add 1 Tbsp olive oil and heat until shimmering but not smoking.

Place chicken breasts in the skillet without overcrowding. Cook undisturbed for 5-6 minutes until deeply golden on the first side.

Turn chicken over and reduce heat to medium. Cook for an additional 4-5 minutes until internal temperature reaches 160°F (71°C). Transfer to a plate and tent loosely with foil.

In the same skillet, add remaining 1 Tbsp olive oil. Add pine nuts and toast for 60-90 seconds until golden, stirring constantly to prevent burning.

Add minced garlic and cook for 30 seconds until fragrant but not browned.

Add chicken stock and lemon juice, scraping up all browned bits from bottom of pan with wooden spoon. Simmer until liquid is reduced by half, about 2 minutes.

Reduce heat to low. Add 1 cup of the basil leaves, remaining ¼ tsp salt, and stir until just wilted, about 30 seconds.

Add cold butter cubes one at a time, swirling pan continuously to create an emulsified sauce.

Return chicken to the pan along with any accumulated juices. Sprinkle with Parmesan cheese and remaining ½ cup fresh basil leaves. Spoon sauce over chicken and serve immediately.