Step 1
Place a rack in lowest position in oven and preheat to 400°. Whisk ¼ cup whole milk, 1 Tbsp. cornstarch, and 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt in a medium bowl until combined and cornstarch is dissolved. Add 8 large eggs and whisk until mixture is smooth and no streaks remain.
Step 2
Melt 4 Tbsp. unsalted butter in a large nonstick skillet over medium-high. Pour in egg mixture and cook, stirring often with a heatproof rubber spatula or wooden spoon, until scrambled and just set, about 4 minutes (eggs should still look a bit runny on top). Transfer scrambled eggs to a small bowl and let cool.
Step 3
Meanwhile, wipe out skillet and melt remaining 2 Tbsp. unsalted butter in skillet over medium heat. Add 1 medium onion, finely chopped, and a large pinch of salt and cook, stirring occasionally, until onion is softened and translucent, about 5 minutes; transfer to another small bowl. Reserve skillet.
Step 4
Stir 3 chipotle chiles in adobo, finely chopped, ⅔ cup refried beans, and ¼ cup finely chopped cilantro into cooked onion; taste and season with more salt if needed.
Step 5
Cook 1 lb. fresh chorizo, casings removed, broken into large pieces, in reserved skillet, breaking up with spatula or spoon, until well browned and cooked through, 8–12 minutes. Transfer to a large plate.
Step 6
Generously coat a 9″–10″-diameter cast-iron skillet with room-temperature unsalted butter. Place four 12″-diameter flour tortillas in pan to cover bottom and sides completely, overlapping as needed to form a shell that extends 2″ above edges of pan.
Step 7
Place 5 slices American cheese on top of tortillas so they cover bottom of pan, tearing to fit as needed. Spoon refried bean mixture over cheese and spread into an even layer. Top with 1 ripe avocado, sliced ¼” thick, arranging in a single layer. Scoop scrambled eggs into skillet and gently spread into an even layer. Scatter chorizo over eggs and top with remaining 5 slices American cheese, tearing to fit as needed. Top cheese with 2 cups salted thick tortilla chips, crushing lightly (you just want to help them fit better; don’t crush them into small pieces). Cover chips with remaining flour tortilla, pressing down gently to compact. Fold tortilla overhang up and over filling to encase.
Step 8
Cover surface of crunchwrap with a large square of foil and place another heavy skillet on top to weigh down (this will prevent tortilla flaps from rising as they brown). Bake crunchwrap until edges are pale golden, 18–20 minutes. Remove top skillet and foil and continue to bake crunchwrap until surface is golden brown, 10–12 minutes longer. Let cool 15–20 minutes (this will allow layers to settle).
Step 9
Place a large plate upside down over skillet and carefully flip skillet and plate over in one motion to invert crunchwrap out onto plate (remember, skillet will be hot, so use dry kitchen towels to prevent any burns).
Step 10
Cut crunchwrap into wedges with a large serrated knife and serve with hot sauce alongside and lime wedges for squeezing over.
Do Ahead: Onion mixture can be made and chorizo can be cooked 1 day ahead. Transfer to separate airtight containers; cover and chill.