Preheat oven to 400 F.
Dice chicken breast in bite sized pieces. Season with salt and pepper. Coat with cornstarch.
Dice onion, slice mushrooms, and cut asparagus.
In a small saucepan, heat the chicken stock so it's at a low simmer.
Heat a large pot or dutch oven to medium-high and add oil.
In two batches, brown the chicken breast. It does not need to cook all the way through. It will finish in the oven.
Remove browned chicken from pot and set aside.
Lower heat to medium and add butter, onions, and garlic to the pan stirring continuously.
While the onions soften, line a sheet pan with parchment paper or nonstick spray. Spread out the mushrooms, asparagus, and chicken onto the sheet pan. Drizzle the veggies with olive oil and season lightly with salt and peppers. Put in the oven and cook for 20 minutes until veggies have cooked through.
Add arborio rice to the pot and stir to coat with butter and onions. Let the rice toast in the butter for about two minutes.
Add the Marsala wine and stir in well. Scrape up all the brown bits from the chicken off the bottom of the pot.
Once the Marsala wine has cooked down, add a full ladle of warm chicken stock to the pot and continuosly stir. The rice and chicken stock mixture should stay at a low bubble throughout the cooking process. Every time the chicken stock has been completely absorbed by the rice, add another ladle. This process will take 25-30 minutes.
Take a little taste of the rice and see if it is cooked through. Add salt or pepper if needed. Once it is cooked through, make sure there is enough liquid to just keep the risotto loose and not stuck together.
Stir in marscapone cheese. It should have a loose and creamy consistency. Next, add in the chicken. Then fold in the asparagus and mushrooms.