Heat the olive oil in a large 12-inch skillet. Season the chicken with salt and freshly ground black pepper. Brown the chicken cubes on all sides. Remove the browned chicken from the pan and set aside.

Add the butter, onion and carrots and sauté for a few minutes, until the onions start to soften. Add the mushrooms, season with salt and freshly ground black pepper and sauté for a few more minutes until all the vegetables begin to soften. Stir in the flour and cook for a minute or two. Add the sherry and bring it to a simmer until the mixture has thickened. Pour in the chicken stock and heavy cream, continue to simmer and stir until the sauce is completely smooth. Stir in the dry egg noodles.

Simmer uncovered for 10 minutes. Return the browned chicken to the pan, add the peas and cook for 2 to 3 more minutes, until the noodles are cooked. Remove the pan from the heat and stir in the Swiss cheese and tarragon. Let it sit for a few minutes. The sauce will thicken a little and it will cool to an edible temperature. Serve with a butter lettuce salad.