Bring a pot of water to a rolling boil. Salt generously. Prepare an ice bath while the water is coming up to a boil.
Drop the green beans into the boiling water for exactly 90 seconds. Remove with a spider or large slotted spoon and immediately drop into the ice bath. This stops the cooking and retains the bright green, pretty color. Remove from the ice bath and drain on paper towels or a clean kitchen towel. You don’t have to be precious about drying them, but you don’t want a lot of water messing up your butter sauce.
Place a large skillet over medium-high heat and add 4 tbs butter. Once it’s melted, add the garlic and stir constantly until it is cooked but not brown, about a minute. Stir in the parsley. Move the heat to medium-low. Add the green beans to the skillet, along with the remaining 2 tbs butter and salt and black pepper to taste. Stir to melt the remaining butter and thoroughly coat the green beans with all that beautiful garlic and parsley butter. Transfer the beans to a serving dish, making sure you don’t leave any garlic butter in the skillet, and serve immediately.