Boil the potatoes and cashews about 8-10 minutes until the potatoes are fork-tender. Drain well and set aside.
Place fettuccine in a large pot of salted boiling water. Cook until al dente (about 10-12 minutes). Drain and drizzle with olive oil to prevent sticking.
Now place all ingredients into a blender (except butter & garlic). Blend until potatoes and cashews have completely broken down and sauce is smooth. Set aside.
Heat up butter in a large pan over medium heat. When melted, add garlic and sauté for 30-60 seconds until lightly brown and fragrant.
Pour cream sauce into the pan. Cook for 3-4 minutes until sauce slightly thickens up. Stir often to prevent burning. Taste for seasoning and add more if needed.
Now add pasta and thawed peas to pan and gently toss to coat. Serve immediately. Enjoy!
Notes
To thaw peas, place in a colander and rinse under cool water for 1-2 minutes.