Preheat oven to 350 degrees F (175 degrees C).

Combine cream cheese and mayonnaise in a large bowl until smooth; stir in garlic. Gently stir artichoke hearts, crab, Parmesan cheese, 1/3 cup green onion, 1/3 cup red bell pepper, and cayenne pepper into cream cheese mixture. Transfer the dip to a 9-inch pie dish and sprinkle top with bread crumbs.

Bake in the preheated oven until crumb topping is golden brown and dip is hot, 20 to 30 minutes. Garnish with 2 teaspoons green onion and 2 teaspoons chopped red bell pepper.