Preheat the oven to 350°F (177°C).
Combine the bell peppers, garlic bulb, onion, and cashews on a large baking sheet.
Drizzle with 1 tablespoon (15 ml) of the olive oil, sprinkle with half of the salt and half of the black pepper, then mix well with your hands.
Spread the mixture into a single layer and bake for 25 to 30 minutes, or until the garlic is golden brown and bell peppers are soft. Once done, remove from the oven and set aside.
While the veggies bake, place a 7-quart soup pot over medium heat. Once hot, add the remaining tablespoon (15 ml) of olive oil, leek, and remaining salt and black pepper, and sauté for 1 minute.
Next, add the portobello mushrooms and cook for 3 to 4 minutes, or until the portobellos are softened. Add the tomatoes, and stir to deglaze the pan. Add the cannellini beans, stir, then add veggie broth and bring to a boil.
Meanwhile, transfer the roasted onion, cashews, and bell peppers to a high-powered blender. Squeeze the garlic cloves into the blender from the bulb and add the plant-based milk. Blend on high speed for 30 seconds, or until smooth. Set aside.
Once the veggie broth is boiling, lower the heat slightly, pour the creamy blended mixture into the pot, and stir.
Break your uncooked lasagna noodles into half or thirds (depending on your preference), add them to the boiling soup, and cook for the duration of their package instructions.
Once the noodles are soft and tender, add the kale and basil, and mix well. Taste for salt. The soup will be done when the kale has softened. Enjoy immediately.