Beat butter and brown sugar until creamy.
Mix in maple syrup, egg yolk, and vanilla.
In a separate bowl, whisk flour, baking soda, cinnamon, and salt. Add to wet mixture and stir until just combined.
Chill dough for 30 minutes.
Preheat oven to 350°F (175°C). Line baking sheet with parchment paper.
Scoop 1 ½ tbsp dough balls, place 2 inches apart, and bake for 9–11 minutes until edges are golden.
Cool on the baking sheet for 5 minutes, then transfer to a wire rack.
Melt white chocolate in 20–30 second microwave intervals until smooth.
Dip half of each cooled cookie into chocolate. Add sprinkles or peppermint.
Let set at room temperature or refrigerate briefly.