Reduce heat to medium. Add garlic and cook 20 seconds. Add miso paste directly to the pan and let it fry in the residual fat 20–30 seconds — this blooms the miso and deepens the flavor. Add chili crisp, soy sauce, sugar, and stock. Stir until the miso fully dissolves and the sauce is smooth and glossy.
Add noodles directly to the sauce. Toss continuously as the liquid reduces and noodles absorb the sauce, 3-5 minutes.
Finish with scallions, sesame seeds, and a heavy chili crisp drizzle.