Heat oil in a skillet over medium heat. Add onion and garlic; cook and stir until onion is translucent, about 5 minutes. Stir in squash and corn; cook, stirring frequently, until squash is softened, about 5 minutes. Transfer to individual serving plates.
Combine Neufchatel cheese, chile peppers, and milk in a blender; blend until sauce is smooth.
Heat sauce in a saucepan over medium heat until warmed through, 2 to 4 minutes; pour over squash mixture.