Shredded beef turns this Mexican favorite into a big meal for your hungry family. A dried chili sauce adds color and deep smoky flavor.
Remove stems from guajillo peppers; discard seeds. Reserve 3 peppers. Place remaining 12 guajillo peppers in large bowl; cover with 8 cups boiling water. Place bowl or plate on peppers to keep them submerged. Cover; soak at least 30 minutes to rehydrate.
Season beef roast with 1/2 teaspoon salt and black pepper. Place roast in 6-quart electric pressure cooker; add reserved 3 guajillo peppers and 1/2 cup boiling water. Close and lock pressure cooker lid. Use beef, stew or high-pressure setting on pressure cooker; program for 90 minutes on pressure cooker timer, following manufacturer's instructions as needed. Use natural release feature to release pressure; carefully remove lid.
Place Anaheim peppers on grid over medium, ash-covered coals; grill peppers, uncovered 6 to 8 minutes (over medium heat on preheated gas grill, covered 10 to 12 minutes) until pepper skins are charred and blistered. Grill corn, uncovered, 15 to 20 minutes or until tender. Place peppers in large food-safe plastic bag. Close bag; let stand 10 to 12 minutes or until cool enough to handle. Remove and discard skins from peppers. Carefully cut 1 slit lengthwise in pepper, leaving top intact and discarding seeds.
Preheat oven to 400°F. Place roast in medium bowl; shred beef using two forks, discarding pockets of fat as desired. Add 1/3 cup cooking liquid; mix well. Set aside.
Coat 13 x 9-inch glass baking dish with cooking spray. Cut corn from cob (about 1 cup). Combine cheese, corn, carrot and cilantro in medium bowl; mix well. Divide shredded beef among 6 Anaheim peppers; top with cheese filling. Fold pepper around filling. Place stuffed chiles, side by side in prepared baking dish, nesting chiles together as needed. Bake in 400°F oven 10 to 15 minutes or until internal temperature reaches 165°F and cheese is melted.
Meanwhile, to prepare Guajillo Chile Sauce, drain soaking water from rehydrated guajillo peppers, reserving 1/2 cup water. Place peppers in blender or food processor container. Add reserved 1/2 cup soaking water and remaining 1/2 teaspoon salt. Cover; pulse on and off until mixture is smooth. Process 1 minute more. Strain through fine mesh strainer.
Divide guajillo sauce among 6 plates. Top sauce with stuffed peppers. Garnish with black olives, if desired.