Preheat oven to 400°. Line a 13x9-in. baking pan with parchment paper, extending paper over edges of pan; set aside.

Place mushroom slices in a medium saucepan; add water to cover. Bring to boil; boil for 4 to 5 minutes or until softened. Drain mushrooms. Place on paper towels; pat dry.

Place mushrooms and walnuts in a food processor or blender. Cover and pulse or blend until finely chopped. Add ketchup, tamari, cayenne pepper, smoked paprika and garlic powder; cover and pulse or blend until smooth.

Heat a large nonstick skillet over medium-high heat. Add mushroom-walnut paste; cook for 3 to 5 minutes or until lightly browned, stirring and breaking into fine crumbles. Stir in olive oil; cook for 2 to 3 minutes or until browned and crumbled, stirring occasionally.

To assemble, spread half of the tortilla chips in prepared baking pan. Layer with half each of Mexican-style shreds and crumbled mushroom-walnut crumbles; repeat layers with remaining chips, Mexican-style shreds and mushroom-walnut crumbles. Bake for 10 to 12 minutes or until shreds are heated through.

To serve, lift edges of parchment paper to remove nachos from baking pan; transfer nachos to a large serving platter. Top with guacamole, chipotle sauce, corn salsa, pickled red onions and lime juice. Garnish with jalapeño peppers and cilantro; serve with lime wedges, if desired.