In a small bowl, combine dry mustard, dried thyme, dried oregano, salt, and black pepper. Pat the chicken pieces dry with paper towels, then coat them evenly with the seasoning mix.

Heat olive oil in a large skillet over medium-high heat. Add the seasoned chicken pieces and sear for about 6-8 minutes on each side until golden brown and cooked through.

In a large pot, bring salted water to a boil. Add the rotini and cook for 8-10 minutes until al dente, then drain, reserving a cup of pasta water.

In the same skillet, melt butter, then whisk in all-purpose flour to form a roux. Gradually add white wine, followed by minced garlic and diced onions, and cook until onions soften.

Slowly whisk in milk, cooking until it bubbles and thickens. Reduce heat and stir in cheddar cheese until melted.

Chop the cooked chicken and add it to the skillet. Fold in the drained pasta and mix until coated in sauce, cooking together for 2-3 minutes.

Plate the Cheesy Chicken Pasta, garnish with dried thyme or red pepper flakes, and serve warm.