Preheat the oven to 230°C.
Melt the milk and butter over medium-low heat.
In a bowl, mix eggs, sugar, and salt together.
Add maple syrup and mix well.
Sift in the flour and knead the dough.
Add the melted milk and butter, and combine thoroughly.
Refrigerate the dough for 24 hours.
Brush butter onto the canelé mold and pour in the batter.
Bake at 230°C for 15 minutes, then continue baking at 180°C for an additional 40 minutes.
Let cool, then remove from the mold.