Preheat the oven to 400°F. Soak cashews in boiling water. Arrange onions, garlic, and tomatoes on a baking tray lined with parchment paper.
Drizzle with 2 tbsp olive oil, pepper, and bake for 30 minutes. Cook pasta according to package instructions in the final 10 minutes. Peel tomatoes when cool enough, then blend with soaked cashews, roasted vegetables, and remaining ingredients until smooth.
Adjust seasoning. Pour sauce over cooked pasta, mix with remaining basil, and garnish as desired. Enjoy!
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