Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper.
Trim the ends of the haricots verts and toss them on the baking sheet with half of the olive oil, a pinch of sea salt, and black pepper.
Roast the green beans for 12-15 minutes until they are tender and slightly blistered.
While the beans roast, season the chicken breast on both sides with the remaining salt and pepper.
Heat the remaining olive oil and the ghee in a stainless steel or cast-iron skillet over medium-high heat.
Place the chicken in the skillet and sear for 5-6 minutes per side until golden brown and the internal temperature reaches 165°F.
During the last 2 minutes of cooking, add the minced garlic, fresh thyme, and lemon juice to the pan, spooning the juices over the chicken.
Remove the chicken from the heat and let it rest for 3 minutes before slicing.
Serve the lemon-herb chicken alongside the roasted haricots verts, drizzling any remaining pan juices over the top.