Dice the onion into 1/2-inch pieces, mince the garlic cloves, slice celery into 1/4-inch crescents, peel and slice carrots into 1/4-inch rounds, and whisk the cornstarch with 1 tablespoon of water in a small bowl until smooth to prevent lumps when added to the soup later. Having everything prepped before cooking begins ensures the sautéing step flows smoothly.

Set your Instant Pot to sauté mode and melt the butter, then add the diced onion, minced garlic, and sliced celery. Cook for 2-3 minutes until softened and fragrant, stirring occasionally. Stir in the garlic powder, dried thyme, Italian seasoning, salt, and black pepper to bloom the dried spices and deepen the flavor. Pour in the chicken broth and add the chicken breast whole—it will be easier to shred after cooking. Seal the pot and pressure cook on HIGH for 8 minutes (this will cook the chicken through while building a flavorful broth base).

Allow the pressure to release naturally for 5 minutes, then carefully quick-release any remaining pressure. Remove the cooked chicken breast with tongs and place it on a cutting board. Let it cool for 1-2 minutes, then shred it using two forks, pulling the meat apart into bite-sized pieces. I find natural pressure release helps the chicken stay incredibly tender rather than tough from the sudden temperature change.

Switch the Instant Pot to sauté mode and stir the shredded chicken back into the pot. Pour in the milk and add the cornstarch slurry from Step 1, stirring constantly for about 1 minute until the soup thickens slightly and becomes creamy—the cornstarch will help create a silky texture without making it heavy. Add the sliced carrots and potato gnocchi, then simmer for 2 minutes until the gnocchi floats and the carrots begin to soften. I like to taste and adjust seasoning at this point since the milk can mellow the spice profile.

Turn off the heat and stir in the fresh spinach, folding it gently until wilted, about 1 minute. Taste and adjust seasoning with additional salt and pepper as needed. Ladle into bowls and serve hot. The residual heat will wilt the spinach perfectly while keeping it bright and fresh rather than overcooked.