Combine the chicken marinade ingredients (olive oil, lemon juice, Worcestershire sauce, Dijon, salt, pepper) in a large freezer bag or bowl and whisk to combine.
Add the chicken to the marinade, toss to coat, then refrigerate for at least 30 minutes or up to 4 hours.
Cook the tortellini in salted boiling water according to package directions until al dente; reserve 1 cup pasta water, then drain.
Preheat the oven to 400°F (200°C). In a medium bowl, whisk 3 tablespoons olive oil, 2 tablespoons finely grated Parmesan, 1/4 teaspoon garlic powder, and 1/8 teaspoon salt. Add cubed baguette and toss to coat.
Spread the coated bread in a single layer on a baking sheet and bake about 10 minutes or until golden and crisp. Set aside.
Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Remove chicken from the marinade, pat dry, and add to the hot skillet; cook undisturbed 3–5 minutes until browned.
Flip the chicken, cover, reduce heat to medium, and cook another 5–7 minutes or until cooked through. Transfer to a cutting board and let rest 5 minutes, then chop or slice.
In a separate large skillet, melt 1 tablespoon butter with 2 tablespoons olive oil over medium heat. Add minced garlic and sauté about 30 seconds.
Sprinkle in 3 tablespoons flour and stir constantly for about 2 minutes to cook the flour.
Lower heat, then slowly whisk in 2 cups milk. Add 1 1/2 tablespoons lemon juice, 1/2 tablespoon Dijon, 1 teaspoon Worcestershire, 1 teaspoon fish sauce, 2 teaspoons chicken bouillon, and all dried seasonings.
Increase heat to medium-high and simmer, stirring constantly, until the sauce slightly thickens.
Reduce heat to low and stir in softened cream cheese until melted, then stir in 1/2 cup freshly grated Parmesan until smooth.
Add the drained tortellini and chopped chicken to the sauce and toss to coat, adding reserved pasta water a little at a time if needed to reach desired consistency.
Taste and adjust seasoning with additional salt, pepper, or lemon juice as needed.
Serve garnished with extra freshly grated Parmesan, croutons, and chopped fresh parsley.