Step 1

Bring a large pot or Dutch oven of salted water to a boil. Add the spaghetti and prepare according to the package instructions; depending on the brand, you may need to boil the noodles or simply soak them in just-boiled water. Drain.

Step 2

In a blender, combine 1 1/2 cups of the peas, the broth or water, half of the mint, the lemon juice, garlic, 1/2 teaspoon of salt and the red pepper flakes, and puree until smooth. Taste, and season with more lemon juice, salt and red pepper flakes, if desired.

Step 3

Return the pot to medium-high heat and heat the oil until shimmering. Pour in the sauce, bring to a simmer, and reduce the heat to medium. Cook until slightly reduced and thickened, about 5 minutes. Add the remaining 2 cups of peas and cook, stirring, until they are thoroughly heated through, about 2 minutes. Add the cooked spaghetti and toss to combine.

Step 4

Divide among individual plates or shallow bowls. Sprinkle with the feta, pistachios, the remaining half of mint and, if desired, another pinch of red pepper flakes and some flaky salt. Serve warm.