Preheat the oven to 400ºF (200ºC). In a large pot, combine corn, bell peppers, 2/3rds of the lime juice, 75% of the chili powder, tomatoes and spinach and cook over medium-high heat until liquid is almost evaporated, about 10 minutes.

Meanwhile, in a large bowl, mash beans and the remaining chili powder and lime juice.

Arrange half of the tortillas on a large parchment paper-lined baking sheet. Spread bean mixture evenly on tortillas. Top each with an even amount of the vegetable mixture and some cheese. Top with remaining tortillas, vegetables and cheese and bake until hot throughout and cheese is melted, about 15 minutes.

Serve with remaining lime wedges.