The extra butter added at the end helps emulsify the sauce, but you can get away with less, if you like.
Melt 2 Tbs. of the butter in a large sauté pan over medium heat. Add the almonds and cook, tossing frequently, until they're light brown and toasted, 3 to 4 min. Transfer them with a slotted spoon to a plate lined with paper towels.
Add the green beans, garlic, and salt to the pan. Toss to coat the beans with the residual butter. Add the water and simmer gently, tossing occasionally, until the beans are fork-tender and fully cooked (taste one to check), about 15 min. The liquid should be reduced to about 1/4 cup or less; if there's too much liquid, increase the heat to a boil and let it reduce briefly. Add the remaining 2 Tbs. butter and toss to coat the beans and emulsify with the liquid. Add the pepper, toss, and adjust the seasonings as needed. Scatter the slivered almonds over the serving platter or over each serving.
nutrition information (per serving):
Photo: Scott Phillips