Scottish Oatmeal Bread

Scant 1 3/4 teaspoons table salt

3/4 teaspoon instant, fast-rising, or bread machine yeast

3/4 teaspoon ground allspice

1/8 teaspoon ground nutmeg

1 1/4 cups plus 2 tablespoons ice water, plus more if needed

1/2 teaspoon finely grated orange zest

2 tablespoons unsalted butter, at room temperature, plus more for greasing pan and loaf top

3/4 cup old-fashioned rolled oats, plus

4 tablespoons for garnish

2/3 cup boiling water

6 tablespoons packed light or dark brown sugar

2/3 cup dried currants, rinsed under hot water, then thoroughly drained and patted dry