Preheat the oven to 350 degrees. Line two baking sheets with parchment paper.
Place the butter and brown sugar in the bowl of a stand mixer fitted with the paddle attachment and beat until combined, about 2 minutes. Add the maple syrup, vanilla and egg. Beat on medium speed until homogenous, about 1 minute more.
Whisk together the flour, apple pie spice, baking soda and salt in a medium bowl. Pour half of the dry ingredients into the butter mixture and beat on low speed until combined. Repeat with the remaining dry ingredients until a loose, wet dough comes together. Allow the dough to rest for about 10 minutes in the refrigerator; it will thicken slightly as the flour becomes hydrated.
Using a 3-tablespoon size scoop, make large mounds of dough on the prepared baking sheets, leaving at least 3 inches of space between each cookie. Place an apple ring on top of each mound and press gently down to secure. Generously sprinkle each apple slice with sanding sugar.
Bake the cookies until deeply golden brown, about 15 minutes, rotating the tray halfway through the baking time. Allow the cookies to cool on the baking sheets for 5 minutes before moving to a wire rack.