Heat olive oil in a Dutch oven over medium-high heat. Add chopped vegetables and cook until tender.: The pan should give you a soft sizzle as the olive oil warms, followed by the bright scent of softened onion , bell pepper , carrots , and celery . As the pieces sweat, you will notice the aroma deepen into a sweeter, roasted vegetable smell, and the edges may start to take on a little color which adds savory notes. This step builds the flavor foundation, because caramelization creates sugars that enrich the broth. A common mistake is using too high a heat, which makes the vegetables brown too fast and risks a bitter taste. If the pan looks like it is sticking too quickly, drop the heat a notch and add a splash of broth to deglaze and capture those browned bits.
Add chicken, cream of chicken soup, chicken broth, water, cajun seasoning, garlic powder, salt, and pepper. Stir.: When you add the shredded or chopped pre cooked chicken , the meat begins to warm and release its juices into the pot. Stirring in the canned cream of chicken makes the liquid turn silkier, and the broth will take on a slightly opaque, creamy look. The scent of cajun seasoning will bloom, offering peppery and aromatic notes that contrast with the gentle umami from the cream soup. It's important to stir thoroughly to dissolve the condensed soup and distribute seasoning evenly. A frequent error here is failing to fully incorporate the canned soup, which can leave gloopy pockets; take a moment to whisk or stir until smooth.
Bring to a boil over medium-high heat. Reduce heat to simmer and cook for 20 to 25 minutes.: As the pot comes to a boil, you'll see active bubbling and a louder, more energetic sound. The aromas will become more pronounced, and the soup will look more cohesive. Reducing to a simmer lets flavors marry without over agitating the liquid, and that gentle movement encourages the vegetables to soften fully and the seasoning to infuse. You should notice the broth smell deeper and slightly reduced after the simmer. Avoid simmering too vigorously, which can break down delicate ingredients and make the chicken stringy.
Stir in dried noodles. Cook for 5 to 10 minutes, until noodles are soft.: Adding the dried fine egg noodles causes the pot to quiet to a gentle murmur as the pasta hydrates. The noodles will swell and absorb some of the creamy liquid, softening to a tender, coated texture that clings to the shredded chicken and vegetables. You will hear the faintest whisper as the pasta finishes cooking, and the visual cue is a return to a slightly thicker, body filled soup. Overcooking makes pasta mushy, and undercooking leaves a firm center, so test a strand for tenderness toward the shorter end of the time range and remove from heat once done.