Position the oven rack towards the top of the oven and preheat to medium broil.

Drizzle 2 teaspoons of honey over each grapefruit half evenly and set them aside.

In a small bowl, combine cold unsalted butter pieces, brown sugar, all-purpose flour, ground cinnamon, nutmeg, and salt. Press the mixture together until it forms soft crumbs.

Sprinkle the prepared crumbs evenly over the honey-drizzled grapefruit halves.

Place the grapefruit halves on a baking pan and broil in the preheated oven until the crumb topping is lightly browned and caramelized, about 8-9 minutes.

Remove from oven and serve immediately.