For the gnocchi: prepare and cook DeLallo Gnocchi kit as package directions.
Prepare mushroom sauce: Add in butter, mushrooms and a sprinkle of salt, and pepper to a medium skillet on medium heat. Cook until mushrooms have lightly browned, about 5-6 minutes. Remove mushrooms and set aside.
Add in 1 tbsp olive oil and sauté onion until softened, about 3-5 minutes. Add garlic and rosemary and cook until fragrant, about 1 minute.
Add the wine to deglaze and loosen any bits off the pan and simmer a few minutes until the wine has almost evaporated. Whisk in the chicken broth, dijon mustard heavy whipping cream and parmesan cheese. Simmer for 5 minutes or until reduced by half.
To thicken the sauce further if desired, combine 2 tsp cornstarch with 2 tablespoons of water (or broth) and mix well. Add cornstarch mixture into the broth a little bit at a time to reach desired consistency. You may not need all of the cornstarch mixture. Taste test for salt and pepper and season accordingly.
Add cooked gnocchis to the sauce and mix together. Top with freshly chopped Italian parsley before serving.