Melt 3 tablespoons butter in a large deep skillet or Dutch oven over medium heat. Add diced onion, sliced carrots, and diced celery. Cook for 5-6 minutes, stirring occasionally, until vegetables soften and onion turns translucent.
Stir in garlic powder, thyme, rosemary, paprika, adobo seasoning, chicken bouillon, salt, and pepper. Cook for 1 minute until fragrant.
Sprinkle ¼ cup flour over vegetables and stir well to coat. Cook for 1 minute to remove raw flour taste, creating a light roux.
Add 1½ cups uncooked orzo to skillet. Slowly pour in 3 cups chicken broth while stirring constantly. Bring to gentle simmer and cook uncovered for 10 minutes, stirring every few minutes, until orzo is tender and most liquid is absorbed. Add more broth if mixture gets too thick.
Stir in 1 cup heavy cream and 2 cups cooked chicken. Cook for 2-3 minutes until sauce is creamy and chicken is warmed through.
Add frozen peas and cook for 1-2 minutes until bright green and tender. Taste and adjust seasoning with more salt or pepper if needed.
Serve immediately, garnished with fresh parsley and grated parmesan if desired. Best enjoyed warm and creamy right off the stove.
