Preheat the oven to 400°F and line a small baking dish with parchment paper. Cut the peaches in half, remove the pits, and arrange the peaches cut-side up in the dish.
Whisk the whisky, melted butter, maple syrup, and cinnamon together until smooth. Brush the mixture over the cut sides of the peaches.
Flip the peaches cut-side down and brush the mixture over their backs. Drizzle any remaining mixture over the peaches, then bake for 10 minutes.
Flip the peaches cut-side up and bake for another 15–20 minutes, until soft and caramelized.
Serve each peach with a scoop of vanilla ice cream, a sprinkle of pecans, and a drizzle of the warm, buttery syrup from the pan.