Place chiles on a foil-lined baking sheet; broil 3 inches from heat 8 minutes or until blackened, turning after 4 minutes. Place in a zip-top plastic bag; seal. Let stand 15 minutes. Peel and discard skins. Cut a lengthwise slit in each chile; discard seeds, leaving stems intact.
Preheat oven to 350°.
Heat a large nonstick skillet coated with cooking spray over medium heat. Add bell pepper; cook 4 minutes, stirring frequently. Add corn, onions, nuts, and garlic; cook 2 minutes, stirring frequently. Remove from heat; stir in 1/2 cup cheese, cilantro, 1/2 teaspoon salt, and 1/8 teaspoon ground red pepper.
Place half of beans in a bowl; mash with a fork. Add mashed beans and whole beans to corn mixture. Spoon about 1/3 cup bean mixture into each chile; fold sides of chile over filling. Arrange stuffed chiles in an 8-inch square baking dish coated with cooking spray; set aside.
Melt butter in a medium saucepan over medium-low heat; add 1/8 teaspoon ground red pepper, cumin, and nutmeg, and stir with a whisk. Cook 30 seconds, stirring constantly. Gradually add flour, and stir with a whisk; cook 5 minutes, stirring constantly. Gradually add milk. Stir with a whisk until blended.
Increase heat to medium. Cook milk mixture 8 minutes or until thick. Remove from heat; stir in 1/2 teaspoon salt and lime juice. Pour milk mixture over stuffed chiles.
Combine remaining 1/4 cup cheese and breadcrumbs; sprinkle over milk mixture. Bake at 350° for 20 minutes or until sauce is bubbly.
Broil 1 minute or until top is golden brown.