Combine agave syrup and milk in a bowl and mix well.
Add eggs and yolks, and stir until well combined.
Add cake flour, sugar, and salt, and mix evenly.
Add melted butter and vanilla bean.
Let the batter rest in the refrigerator for 24 hours.
Brush butter onto canelé molds and pour in the batter.
Bake at 190°C for 50 minutes.
Cool and unmold.