Season chicken breasts with salt and pepper. In a large skillet over medium-high heat, add a tablespoon of butter and sear the chicken for about 6–7 minutes on each side until golden brown. Remove from skillet and set aside to rest.

In the same skillet, melt another tablespoon of butter over medium heat. Add diced carrots, celery, and onion, sautéing for about 5–7 minutes until softened. Stir in minced garlic, cooking for an additional minute.

Sprinkle flour over the sautéed vegetables, stirring to coat them evenly. Cook for about 1–2 minutes until flour turns a light golden color. Gradually whisk in chicken stock, scraping up any flavorful bits stuck to the pan.

Return the seared chicken to the skillet with fresh herbs. Reduce heat to low and let simmer for about 15 minutes, allowing the chicken to infuse the sauce with flavor.

Carefully remove the chicken and herb bundle from the skillet. Shred the chicken into bite-sized pieces and stir back into the creamy sauce along with frozen peas. Cook for an additional 3–4 minutes until peas are tender.

Boil pappardelle according to package instructions in salted water until al dente, usually about 3–5 minutes. Once cooked, drain the pasta and add directly to the skillet, tossing to coat in the sauce.