Trim asparagus ends and cut asparagus tips, set aside. Cut asparagus spears into 1/2 inch pieces.
Trim and discard dark greeen park of leek, then halve the remaining stalk lengthwise and thinly slice.
Halve lemon.
Grate parmesan cheese.
In a Dutch oven, melt 1 piece butter over medium-high heat. Add asparagus tips, saute for 2 minutes, stirring occassionally. Transfer asparagus tips to plate or bowl.
Add remaining butter, leeks, and asparagus spears to Dutch oven over medium-low heat. Season with a dash of salt and pepper. Cook for 10 minutes, stirring occassionally.
Dissolve bouillon in 2 cups hot water to make broth. Stir broth into Dutch oven, increase to medium-high heat until broth comes to a boil, then reduce to medium-low heat and let simmer 5 minutes.
Stir in peas and Parmesan cheese.
Blend or puree soup until smooth, about 1 minute. Add soup back to pot. Stir in asparagus tips, and heavy cream.