Preheat oven to 400 degrees F with an oven rack in the center position.
Cut each ham steak in half. Drain the pineapple, reserving the juice.
Melt 1 tablespoon butter in a large skillet over MEDIUM heat. Add two ham steaks and cook, about 2 minutes per side, or until lightly browned. It's okay if the butter browns, but reduce the heat under the skillet if it begins to burn. Transfer the ham steaks to a large baking dish and repeat with the remaining butter and ham steaks.
Off the heat, add the brown sugar, mustard, allspice, and 2 tablespoons reserved pineapple juice (reserve remaining juice) to the browned butter in the skillet. Place over LOW heat and cook, stirring constantly, for a minute, or until the brown sugar has melted. Remove from the heat and allow it to rest for a couple of minutes. The glaze should be thickened, but thin enough to pour off the end of a spoon on to the ham steaks.
Top each piece of half with a pineapple slice then drizzle the glaze over the ham and pineapple, smoothing it out with the back of a spoon (be sure there’s a little glaze on the pineapple and in the center of the ring). If glaze is too thick, add a little of the reserved pineapple juice to thin it, as needed. Try to get most of the glaze on the ham steaks, not the bottom of the baking dish.
Transfer the ham steaks to the oven and cook for 10 minutes. Switch the oven to BROIL and cook until the glaze is bubbling, 2 to 3 minutes. Remove from the oven and let the ham steaks rest in the baking pan for 5 to 10 minutes before serving.