Preheat the oven to 350°F. Line a standard 12-cup muffin tin with paper liners.

In a large bowl, whisk together the flour, sugar, baking powder, salt, and apple pie spice.

In a separate bowl, whisk the eggs, oil, apple cider, and buttermilk until combined.

Pour the wet ingredients into the dry ingredients and stir just until a few small lumps remain. The batter will look slightly thin.

Divide the batter evenly among the muffin cups, filling each about two-thirds full.

Bake for 20 to 22 minutes, or until a toothpick inserted in the center comes out mostly clean.

Let the muffins rest in the pan for 5 minutes, then transfer them to a wire rack to cool.

Place the melted butter in a small bowl.

In another bowl, stir together the granulated sugar and apple pie spice.

Once the muffins are mostly cool, dip the top of each muffin into the melted butter, then roll it in the sugar-spice mixture to coat.

Return the muffins to the rack and let the topping set before serving.