Preheat the oven to 350°F (180°C).In a large bowl, sift together the flour, spices, and salt, baking soda, and baking powder.In an electric mixer, mix together the butter and brown sugar.Add the eggs and molasses, mix. Reduce the speed and add the flour-spice-salt-baking soda-baking powder mixture. Incorporate well.Shape small balls in the palm of your hand and place them on a parchment-lined baking sheet. Refrigerate for 15 minutes.Bake the spice buns for 8 to 10 minutes.