Preheat oven to 400° F (200° C). Lightly grease a 3-quart casserole dish and set aside.
To soak cashews, boil water in a small pot and remove from heat. Add cashews and cover for 15-20 minutes, until softened. (*See note)
Place macaroni in a large pot of salted boiling water. Cook until al dente & according to package directions (about 9-10 minutes). Drain and cool with water. Drizzle and gently toss with olive oil to prevent sticking. Set aside.
Combine the melted butter and breadcrumbs in a small bowl. Set aside.
Drain and rinse cashews (discard soaking water). Now place all the cheese sauce ingredients in a high-speed blender. Blend until cashews have completely broken down and the sauce is smooth, about 1-2 minutes.
Melt butter in large pot over medium heat (I used the same pot I cooked the macaroni in). Now add minced garlic & sauté for 1-2 minutes, until lightly brown (be careful not to burn).
Pour in cheese sauce and cook for 4-5 minutes, until sauce thickens up. Stir often to prevent burning. Taste for seasoning, and add more if needed. Remove from heat. Pour the cooked macaroni into the cheese sauce and gently stir to combine.
Now evenly pour into the greased casserole dish. Sprinkle with prepared breadcrumbs and place in the oven uncovered for 25-30 minutes, until heated throughout and the breadcrumbs are golden (*Rotate casserole dish a few times for even browning). *Optional: You can broil the top for 2-3 minutes to make it super crispy, just watch very carefully so it doesn't burn. Remove from oven and serve. Enjoy!