Bring a large pot of water, along with the salt, to a rapid boil. Add in green beans and allow to cook for 5 minutes, until bright green and tender. Transfer to a colander and allow to cool.
In a large skillet, melt the butter over medium heat. Add in pine nuts and allow to cook, stirring often until golden brown, about 4 minutes. Add in ¼ cup pesto and stir until incorporated. Add green beans to the skillet and toss until coated and warmed through, about 2 minutes.
Transfer to a large plate, top with remaining pesto and flakey salt. Serve immediately.