Ingredients

• 1/4 cup pistachios
• 12 oz. orecchiette
• Kosher salt
• 12 oz. peas (such as shelled fresh or frozen English and/or halved sugar snap)
• 3 Tbsp. unsalted butter
• 2 Tbsp. extra-virgin olive oil, plus more for drizzling
• 2 medium leeks, white and pale green parts only, cut in half lengthwise, thinly sliced
• 3 garlic cloves, thinly sliced
• 1/2 tsp. crushed red pepper flakes
• 1 small bunch mint, divided
• 3/4 cup buttermilk
• 3 oz. Parmesan, finely grated, plus more for serving
• Freshly ground black pepper
• 2 Tbsp. fresh lemon juice.

Instructions

1. Preheat oven to 350°F. Toast pistachios on a rimmed baking sheet, tossing once, until golden brown, 5–8 minutes. Let cool, then coarsely crush with a measuring cup or glass.
2. Cook pasta in a large pot of boiling salted water 6 minutes, then add peas and cook until pasta is al dente, about 2 minutes more.
3. Meanwhile, heat butter and 2 Tbsp. oil in a medium heavy pot over medium. Cook leeks, garlic, red pepper flakes, and 3 mint sprigs, stirring occasionally, until leeks are soft but not browned, 6–8 minutes; season with salt. Add buttermilk; bring to a simmer. Pluck out mint; discard.
4. Using a slotted spoon, transfer pasta and peas to leek mixture. Add 3 oz. Parmesan; cook, stirring vigorously and adding a little pasta water if needed, until sauce is creamy and coats pasta, about 1 minute. Season with salt and pepper. Remove from heat; add lemon juice. Pull leaves from remaining mint sprigs, tear into pasta, and toss. Divide pasta among bowls. Top with pistachios and Parmesan; drizzle with oil.