Set oven rack about 6 inches from the heat source and preheat the oven's broiler.

Melt butter with sesame oil in a skillet over medium heat. Season butter mixture with garlic powder, salt, and pepper. Cook and stir shrimp, cashews, and green chile peppers in the butter mixture until everything is hot and coated in butter, about 5 minutes.

Arrange tortilla halves into a baking dish. Top each tortilla half with half the avocado slices. Spoon about half the shrimp mixture atop each portion of avocado, drizzling any remaining melted butter from the skillet over the mixture. Top each with about half the pepperjack cheese and Cheddar cheese.

Cook under the preheated broiler until the cheese is bubbling and the edges of the tortilla browning, about 5 minutes.