Heat a large skillet over medium-high heat. Add the oliveoil and brown the mushrooms. Remove to a bowl and set aside.
Add the groundbeef and brown. Discard all but 1 teaspoon of fat. Bring back to medium high heat and add the noodles, milk, beefstock, mushrooms, cornstarch, salt, pepper and paprika. Stir to combine and cover. Lower the heat to medium and allow to simmer for 10-12 minutes, or until the noodles are cooked through.
Add the sourcream and simmer for 5 more minutes. Serve immediately.