Pre-heat the oven to 425 degrees F (215 C). Reconstitute cranberries in 1/2 cup hot water.
Bring a large pot of water to a boil; add salt.
Toss green onions with 1 tablespoon of olive oil in a large skillet over medium heat, season with salt and black pepper. Place green onions on a sheet tray and roast in the oven until lightly charred, about 10 minutes.
Remove green onions from the oven and let them cool down.
Combine green onions, cashews and Parmigiano-Reggiano cheese in a blender, pulse for 5 seconds. Drizzle in the remaining olive oil and season with salt and black pepper to taste. Add ice cubes and puree to make pesto.
Remove pesto from the blender and place it in a large bowl.
Cook pasta according to the package directions. Drain pasta and reserve 1/2 cup pasta cooking liquid.
Add pasta cooking liquid, pasta and drained cranberries to the pesto, stir to combine before serving.