I start by whisking the flour, parmesan, garlic powder, salt, and pepper together in a shallow dish. Each chicken breast gets pressed into the mixture on both sides, then I shake off any extra flour so the coating stays thin and crisp. Into a hot skillet with olive oil it goes, cooking about 4 to 6 minutes per side depending on thickness, until it's deeply golden and cooked through.
While the chicken cooks, I combine the lemon juice, minced garlic, red pepper flakes, and Italian seasoning in a small saucepan over medium heat. I let this simmer down until it reduces to roughly three tablespoons, which only takes a couple of minutes. Then I add the cold butter a piece at a time, swirling the pan constantly so it melts slowly instead of separating.
Once the chicken is out of the skillet and resting on a plate, I toss the lemon slices into the same pan to pick up all those browned bits left behind. The green beans go in next, cooking for 3 to 5 minutes until they're tender but still have a bit of bite. A little more salt, pepper, and garlic powder rounds out the flavor.
I pile the chicken back on top of the green beans right in the skillet, then spoon the warm lemon butter sauce generously over everything. If I'm serving individual plates instead, I drizzle the sauce over each portion right before it goes to the table so it stays glossy and doesn't soak in too fast.