Preheat the Oven: Preheat the oven to 425 degrees F.
Sauté the Scallions: Heat the olive oil in a small sauté pan over medium heat. Add the scallions and cook them for 2 to 3 minutes, until they become fragrant and begin to take on some color. Remove the pan from the heat and let the scallions cool.
Make the Whipped Ricotta: Add the pistachios, parmesan, garlic, salt, black pepper, lemon juice, and ricotta to a food processor. Blend the mixture until smooth. Add the cooled scallions along with the oil from the pan and blend again until fully combined and creamy.
Prepare the Asparagus: Wash the asparagus and trim or snap off the woody ends. Place the asparagus on a sheet pan and toss it with the olive oil and salt, until evenly coated.
Roast the Asparagus: Roast the asparagus for 8 to 10 minutes, until it is tender but still has a slight bite. Remove it from the oven, let it cool slightly, then cut it into 1-inch pieces.
Toast the Bread: Toast the bread slices until they are golden and crisp.
Assemble the Toasts: Spread about 2 tablespoons of whipped ricotta onto each slice of toast. Top with the chopped asparagus.
Serve: Serve the toasts immediately while the bread is crisp and the toppings are fresh.