In a small bowl, combine dry mustard, dried thyme, dried oregano, salt, and freshly ground black pepper. Set aside.
Slice chicken breasts into thin strips or cut into 1-inch cubes. Sprinkle with seasoning mixture.
In a large skillet, heat olive oil, and cook chicken for a few minutes or until cooked and browned. Transfer cooked chicken to a plate. Set aside.
Fill a large pot with water and bring to a boil. Add salt and rotini. Cook according to the package directions until al dente. Drain and set aside.
Melt butter in the same skillet in which you cooked chicken. When melted, add all-purpose flour and mix it together. Then, add dry white wine, minced garlic, diced onions, and Dijon mustard. Mix to combine. Cook for 3-5 minutes or until onions soften. Then, slowly pour milk in a few additions. Stir after each addition.
Cook on low for 4-6 minutes or until thickened. Then, add shredded white cheddar cheese. Mix and cook until melted
Finally, add cooked chicken and pasta. Mix until completely covered with creamy and cheesy sauce. Serve immediately. Sprinkle with fresh thyme, crushed red pepper flakes, or smoked paprika.
