Start by adding the butter to your large skillet over medium-low heat. Allow it to melt and cook, swirling the pan often, for about 4-5 minutes until it turns a lovely golden brown and gives off a nutty scent. Add the sage leaves and let them fry for about 15 seconds before adding the mushrooms with a pinch of salt and pepper.
Increase the heat to medium-high and cook the mushrooms until they start to brown, which takes about 6-8 minutes. Push the cooked mushrooms to one side of the skillet and add the ground turkey to the other side. Let the turkey brown on one side for 3-4 minutes before breaking it apart with a spoon to cook it through.
Once the turkey is fully cooked with no pink remaining, mix it with the mushrooms. Add the Italian seasoning, orzo, lemon juice, and dijon mustard. Stir everything together for a minute or two, allowing the orzo to toast slightly in the pan.
Pour in the chicken broth, making sure to scrape up any browned bits from the bottom of the pan. Continue cooking and stirring occasionally for about 10-12 minutes, until the orzo is al dente. If the liquid absorbs before the pasta is cooked, add more broth a tablespoon or two at a time.
Reduce the heat to low and stir in the milk. Gradually add the freshly grated cheese, stirring continuously until it melts into a smooth, creamy sauce. Finally, fold in the chopped fresh parsley and season with salt and pepper to your liking.