Instructions

1. Arrange a rack in the middle of the oven and heat the oven to 400ºF. Line a rimmed baking sheet with aluminum foil. Brush the foil with olive oil or coat with cooking spray.
2. Thinly slice 2 medium scallions and set aside for garnish. Grate 5 ounces sharp cheddar cheese on the large holes of a box grater (about 1 1/2 cups). Grate 4 ounces Monterey Jack cheese on the large holes of the grater (about 1 cup). Cut the core from 1/2 medium head green cabbage, then cut into thin shreds. Cut 6 ounces raw peeled and deveined shrimp into 1/2-inch pieces.
3. Heat 1 tablespoon of the olive oil in a large frying pan over medium heat until shimmering. Add the shrimp and cook until just opaque and cooked through, about 2 minutes. Transfer to a small bowl.
4. Wipe out the pan with a paper towel and return it to the stovetop over medium heat. Add the remaining 2 tablespoons olive oil and cabbage to the pan. Season with 1 teaspoon kosher salt and 1/2 teaspoon black pepper and sauté, stirring frequently, until the cabbage is wilted and lightly browned, about 6 minutes.
5. Add the shrimp and 1 teaspoon red pepper flakes and stir until combined. Remove the pan from the heat.
6. Assemble the nachos: Arrange half of a 14-ounce bag of tortilla chips on the baking sheet in an even layer. Sprinkle evenly with half the Monterey Jack cheese, half the cheddar cheese, and half of the shrimp and cabbage mixture. Sprinkle with 1 1/2 teaspoons of the shichimi togarashi. Repeat layering the remaining chips, cheeses, and shrimp and cabbage mixture.
7. Bake until the cheeses are completely melted and the edges of the tortilla chips start to blister, 5 to 6 minutes.
8. Drizzle about 1/4 cup tonkatsu sauce over the nachos. Squeeze Kewpie mayonnaise over the nachos on a slight diagonal in zigzagging lines. Sprinkle evenly with the remaining 1 1/2 teaspoons shichimi togarashi and 2 (.176-ounce) packets bonito flakes. (Don’t be alarmed when they start to move around! That’s the sign of a nice hot platter of okonomiyaki or, in this case, nachos!.) Garnish with the scallions and a light scattering of sliced pickled jalapeños if using.
9. Tonkatsu sauce: Use okonomiyaki sauce instead of tonkatsu sauce.
10. Kewpie mayonnaise: Use regular mayonnaise or for the full flavor effect of Kewpie, mix regular mayo, rice vinegar, and granulated sugar together to taste.
11. Scallions: Finely chopped fresh cilantro can be used in place of the scallions.
12. Pickled jalapeño slices: Use quick pickled onions in place of the pickled jalapeño slices.