Place the beans in a colander and rinse under cold running water. Drain.
Heat 3 tablespoons of the oil in a large skillet over medium heat. Add the onions and 1 1/2 teaspoons of the garlic and cook until soft and fragrant, about 2 minutes. Add the drained beans, 4 teaspoons of the lemon juice, 1/4 teaspoon of the salt, the black pepper and cayenne, and cook, stirring, until softened and warmed through, 3 minutes. Remove from the pan and transfer to a decorative platter. Sprinkle with the Parmesan.
In a blender or bowl of a small food processor, combine the parsley, remaining 1 1/2 teaspoons of garlic, 2 teaspoons of lemon juice and 1/4 teaspoon of salt in a blender or small food processor. Process on high speed for 30 seconds. Add the remaining 1/3 cup oil with the motor running and process until smooth. Adjust seasoning, to taste.
Drizzle the parsley pesto over the beans and serve with the toast for dipping.
Yield: 6 servings