Cook the rice noodles according to package directions until just tender. Drain, rinse, and toss with a little oil to prevent sticking. Set aside.

Pat chicken dry, then toss with cornstarch, salt, and pepper.

In a large skillet, melt 2 tbsp butter over medium-high heat. Add chicken in a single layer and cook until golden and cooked through. Remove and set aside.

In the same pan, add remaining butter. Sauté garlic, shallot, and bell peppers until softened and fragrant, about 3–4 minutes.

In a small bowl, whisk soy sauce, sweet chili sauce, rice vinegar, sesame oil, ginger, red pepper flakes, and 2 tbsp water. Pour into skillet and let simmer 1–2 minutes.

Add chicken back to the skillet along with noodles. Toss well until coated and glossy.

Stir in scallions and Thai basil. Garnish with sesame seeds before serving.