For the streusel: In a medium bowl, whisk together the flour, brown sugar, cinnamon, ginger, nutmeg, cloves, and salt. Add the vanilla and melted butter to the flour mixture, stirring until the mixture resembles wet sand. Cover and chill the streusel for at least 30 minutes and up to 1 day ahead.

For the muffins: Preheat the oven to 425°F. In a medium bowl, whisk together the buttermilk, molasses, melted butter, oil, brown sugar, egg, and vanilla.

Whisk together the flour, cinnamon, ginger, nutmeg, cloves, baking soda, and salt in a large bowl.

Add the wet ingredients to the dry ingredients, and stir just until combined. Spoon the batter evenly into a standard 12-cup muffin tin lined with paper liners.

To bake immediately: Top the muffin batter evenly with the streusel, then sprinkle evenly with the turbinado sugar. Bake the muffins for 5 minutes. Reduce the oven temperature to 350°F, and continue baking until a wooden pick inserted in the center of a muffin comes out clean with a few moist crumbs attached, 14 to 16 minutes. Remove the muffins to a wire rack to cool completely, about 30 minutes.

To make ahead: Cover and refrigerate the muffin tin for up to 12 hours. Preheat the oven to 425°F. Let the muffins sit at room temperature for 30 minutes. Top the muffin batter evenly with the streusel, then sprinkle evenly with the turbinado sugar. Bake the muffins for 5 minutes. Reduce the oven temperature to 350°F, and continue baking until a wooden pick inserted in the center of a muffin comes out clean with a few moist crumbs attached, 16 to 20 minutes. Remove the muffins to a wire rack to cool completely, about 30 minutes.

For the glaze: In a medium bowl, whisk together the powdered sugar, salt, vanilla, and half-and-half until smooth. Drizzle the glaze evenly over the cooled muffins.