Cook the Pasta: Bring a large pot of salted water to a boil, then add your pasta. Cook according to package directions until al dente, usually about 8-10 minutes. Drain and set aside.

Sauté Vegetables: In a skillet, heat olive oil and 1 tablespoon of butter over medium-high heat. Add diced onion and sliced cremini mushrooms. Sauté for 8-10 minutes until beautifully browned and their moisture has evaporated.

Add Flavoring: Stir in the remaining tablespoon of butter, minced garlic, and Dijon mustard. Cook for about 1 minute, allowing those enticing aromas to fill your kitchen.

Make the Sauce: Pour in the chicken broth (or vegetable broth/white wine), alongside the lemon juice and zest. Let everything simmer for about 1 minute, bringing those flavors together.

Combine and Serve: Remove from heat, generously fold in grated parmesan cheese and chopped parsley. Toss the cooked pasta with the mixture, ensuring every strand is deliciously coated. Season with salt and pepper to taste, and serve immediately!