Place the raw cashews in a bowl. Cover with boiling water (the 1 cup of water will be used later, just use enough boiling water to cover the cashews) and let sit for 30 minutes. You can make the pasta and tomato-meat sauce in the meantime.
Preheat the oven to 350F. Cook the pasta according to package instructions - but subtract a minute or so from the boil time so the pasta is al dente.
In a large skillet, add 1 tablespoon olive oil along with the Italian sausage and onion. Cook, breaking up into small pieces until browned and cooked through, about 6-8 minutes. Add the garlic, Italian seasoning, red pepper flakes, marinara sauce and diced tomatoes. Cook until heated through for another 5 minutes or so. Remove from heat and set aside.
Drain the cashews and place in a high-speed blender. Add 1 cup of fresh water along with the olive oil, lemon juice, and salt. Blend until completely smooth. Add the eggs and blend until smooth. (The sauce will look very liquidy and runny but will set up in the oven.)
Add a scoop of the tomato-meat sauce to the bottom of a 9x13 pan. Spread out evenly. Mix the pasta with ⅓ of the remaining tomato-meat sauce. Pour half of the pasta into the pan. Drizzle over half of the cashew sauce followed by another ⅓ of the sauce mixture. Add the remaining pasta followed by the rest of the cashew sauce and tomato-meat sauce.
Bake for 25-30 minutes until golden and bubbly. Let sit for 10 minutes before serving. Enjoy!