Crostini with Asparagus Spread and Prosciutto

1 pound asparagus, trimmed
1 large leek (white and light green part only)
4 teaspoons olive oil, divided
1 clove garlic, roughly chopped
1/4 cup ricotta cheese
3 tablespoons lemon juice
salt and pepper
1/2 pound prosciutto
1 loaf of ciabatta bread, sliced, or baguette rounds

Boil the asparagus in a shallow pan for about 5 minutes, until tender and bright green. Remove from pan and put in an ice bath or run under cold water to stop the cooking. Pat dry.

Slice the trunk of the leek lengthwise and reserve one half for another use. Chop the remaining half. In a saut? pan, heat 2 teaspoons of olive oil over medium heat. Add the garlic and leeks, season with salt and pepper, and cook until soft but not brown, about 6 to 8 minutes.

Roughly chop the cooled asparagus and add to the bowl of a food processor. Add the ricotta and leek-garlic mixture and pulse until combined. Add the lemon juice and remaining 2 teaspoons of olive oil. Pur?e until smooth, then add salt and pepper to taste.

To serve, butter slices of bread and toast until golden. Spread a dollop of asparagus pur?e on each slice, then top with a piece of prosciutto.