Preheat oven to 350°F. Line a 9×5-inch loaf pan with parchment paper, leaving overhang for easy removal.

In a small bowl, combine the brown sugar and pumpkin pie spice. Set aside.

Separate each biscuit horizontally to create two layers, yielding 16 biscuit rounds total.

Brush one side of each biscuit round with melted butter. Spread about 1 tablespoon of apple butter over the buttered side, then sprinkle evenly with the spiced sugar mixture.

Arrange the biscuit rounds vertically in the prepared loaf pan, cut sides facing up and slightly overlapping.

Bake for 40–45 minutes, or until the bread is deep golden brown and baked through. If the top browns too quickly, loosely tent with foil.

Let cool in the pan for 10 minutes, then carefully invert onto a cooling rack.

In a small bowl, whisk together powdered sugar, milk, maple syrup, and vanilla extract until smooth. Drizzle over the warm loaf before serving.