PreparationFor the brodo: Bring chicken bones and 12 cups cold water to a gentle simmer (you don’t want it to boil) in a large pot. Reduce heat to medium-low and cook at a bare simmer, skimming foam occasionally, until stock is reduced by one-third, 2 1/2–3 hours. Add spring onions, garlic, prosciutto, and mushrooms to pot and cook another 20 minutes. Strain stock through a fine-mesh sieve into a medium bowl; discard solids (you should have about 9 cups). Pour 3 cups brodo into an airtight container; reserve for another use. Do Ahead: Brodo can be made 3 days ahead. Cover and chill. For assembly: Heat 1/3 cup oil in a medium skillet over medium. As soon as the oil begins to look glossy, add bread slices and cook until golden brown, about 3 minutes per side. Transfer to a plate and season lightly with salt. Pour brodo into a large saucepan and bring to a simmer over medium heat. Taste and season with salt. Add asparagus and cook until tender and bright green, about 3 minutes. Remove from heat; add mushrooms. Toss pea shoots and lemon juice in a medium bowl; season with salt. Divide soup among bowls and place a piece of fried bread into each one. Top with dressed pea shoots and Parmesan. Drizzle with lots of oil and season with pepper.
PreparationFor the brodo: Bring chicken bones and 12 cups cold water to a gentle simmer (you don’t want it to boil) in a large pot. Reduce heat to medium-low and cook at a bare simmer, skimming foam occasionally, until stock is reduced by one-third, 2 1/2–3 hours. Add spring onions, garlic, prosciutto, and mushrooms to pot and cook another 20 minutes. Strain stock through a fine-mesh sieve into a medium bowl; discard solids (you should have about 9 cups). Pour 3 cups brodo into an airtight container; reserve for another use. Do Ahead: Brodo can be made 3 days ahead. Cover and chill. For assembly: Heat 1/3 cup oil in a medium skillet over medium. As soon as the oil begins to look glossy, add bread slices and cook until golden brown, about 3 minutes per side. Transfer to a plate and season lightly with salt. Pour brodo into a large saucepan and bring to a simmer over medium heat. Taste and season with salt. Add asparagus and cook until tender and bright green, about 3 minutes. Remove from heat; add mushrooms. Toss pea shoots and lemon juice in a medium bowl; season with salt. Divide soup among bowls and place a piece of fried bread into each one. Top with dressed pea shoots and Parmesan. Drizzle with lots of oil and season with pepper.