Prepare the Sauce: In a medium bowl, whisk together honey, soy sauce, hoisin sauce, minced garlic, rice vinegar, sesame oil, ginger, and red pepper flakes (if using). This creates the flavorful honey garlic sauce that will infuse the chicken.
Add Chicken to Crockpot: Place the chicken breasts in the bottom of your slow cooker. Pour the honey garlic sauce over the chicken, ensuring all pieces are well-coated.
Cook: Cover and cook on low for 6-7 hours or high for 3-4 hours, until the chicken is tender and fully cooked (internal temperature should reach 165°F/74°C).
Shred the Chicken: Once cooked, remove the chicken from the crockpot and shred it using two forks. Return the shredded chicken to the crockpot to soak up the sauce.
Thicken the Sauce: In a small bowl, mix the cornstarch with 2 tablespoons of water to create a slurry. Stir the slurry into the crockpot and cook on high for an additional 15-20 minutes, until the sauce thickens slightly.
Cook the Noodles: While the sauce thickens, cook your noodles according to the package instructions. Drain and set aside. If adding vegetables, steam or sauté them lightly to retain their crunch.
Combine and Serve: Toss the cooked noodles with the chicken and sauce in the crockpot, or serve the chicken and sauce over a bed of noodles. Garnish with sliced green onions and sesame seeds for a pop of flavor and presentation.