Rinse the asparagus and snap the tough ends of the bottoms of the stalks. Cut the asparagus into 1” to 2” pieces.
Melt 2 tablespoons of the butter with 2 tablespoons of the olive oil in a stockpot over medium heat. Season with ¼ teaspoon of the kosher salt and ¼ teaspoon of the black pepper. Sauté until the asparagus is tender when pierced with the tip of a sharp knife, about 7 minutes. Transfer the asparagus to a heatproof bowl.
Add the remaining butter and olive oil to the stockpot. Toss in the mushrooms and shallots and sauté until the mushrooms are golden and the shallots are translucent, about 8 to 10 minutes. Season with ¼ teaspoon kosher salt and the remaining black pepper. Transfer to the bowl with the asparagus.
Pour the chicken stock into the stockpot, bringing it to a gentle boil. Stir in the tortellini, the remaining kosher salt, and cook, stirring frequently, until tender,about 2 to 4 minutes. (If you’re using dried tortellini, the time will vary.)
Using a slotted spoon, transfer the tortellini to the bowl with the vegetables.
Raise the heat to medium-high and allow the stock to reduce down to about 1 cup, about 10 to 12 minutes.
Pour 1-½ cups of the cream into the reduced stock. Stir inthe nutmeg, lemon zest, and lemon juice. Cook for about 10 minutes to allow the sauce to thicken slightly.
Stir in the chopped chicken, cheese, parsley, the sautéed vegetables,and the tortellini. Add the remaining cream if needed to completely coat the pasta.
Check for seasoning, adding more kosher salt or pepper to suit your taste.
Serve with extra cheese and parsley.