Pat 4 to 6 bone-in, skin-on chicken thighs (or 1½ pounds boneless, skinless chicken breasts or thighs) dry with paper towels and season both sides with 1 teaspoon kosher salt, ½ teaspoon black pepper, 1 teaspoon garlic powder, and 1 teaspoon onion powder.
Heat 2 tablespoons olive oil in a large skillet over medium heat. Sear chicken until golden brown on both sides and nearly cooked through (about 5 to 6 minutes per side depending on thickness). Remove to a plate.
In the same pan, melt 1 tablespoon butter and add 3 to 4 minced garlic cloves. Sauté for 30 to 60 seconds until fragrant.
Add 1 ¼ cups orzo to the pan and toast for 1 to 2 minutes (optional but recommended).
Add 2 cups chicken broth and 1 cup milk (or half-and-half). Stir, scraping up any browned bits from the bottom of the pan. Bring to a simmer, then reduce heat to low and cover. Cook about 10 minutes, stirring occasionally, until orzo is tender and creamy. If it looks dry, add a splash more broth or milk.
Stir in 3 to 4 cups roughly chopped fresh spinach and 1 (14-ounce) can drained and chopped artichoke hearts. Cook until spinach wilts, about 1 to 2 minutes.
Reduce heat to low. Stir in ½ cup grated parmesan cheese and ½ cup cream cheese or mascarpone (cut into small pieces) until melted and smooth. Season to taste with additional salt, black pepper, and juice of ½ lemon (if using).
Slice or shred chicken and return it to the pan. Stir to coat in the creamy sauce. Simmer 2 to 3 minutes until heated through.
Sprinkle with more parmesan cheese and cracked black pepper before serving immediately.