In a medium stock pot, combine milk and split vanilla beans. Cook over medium heat until bubbling and hot.
Meanwhile, whisk eggs, egg yolks, maple sugar, and salt in a large bowl until smooth. Stream in your warm, melted brown butter and whisk to combine.
Slowly add 1/4 of your hot cream and vanilla mixture and whisk to combine. Don't add too much at once or you risk scrambling your eggs.
Whisk in your flour until there are no lumps left. Then, add the rest of your hot cream and mix. Lastly, add your maple syrup and let you custard cool.
Cover your custard and let rest in the fridge for at least 24-28 hours to develop flavor (it can last up to 4 days).
When ready to bake your canelés, combine your food-grade beeswax and butter in a stock pot. Heat over medium until fully melted and warm.
Prepare to coat the insides of your copper canelé tins by ensuring they are room temperature. I place mine in a warm oven until I'm ready to pour in the wax mixture to make sure it doesn't harden too quickly.
Carefully holding your warm copper tins with a kitchen cloth, pour in enough beeswax and butter mixture to fill the cup most of the way. Swirl the mixture around the edges to coat completely, then pour into your next tin.
Repeat coating the insides of your canelé tins until all 6 are filled. They should have a uniform yellow wax coating but not be too thick, which can contribute to your pastries burning. Chill tins until ready to fill.
Preheat oven to 525°F for at least 30 minutes before cooking. Place a tinfoil-lined baking sheet in the oven to heat up, which your tins will sit on.
Remove your custard mixture from the fridge and gently mix it with a fork or chopstick to ensure the flour hasn't sunk to the bottom. Be mindful not to whip it, as you don't want to add any air to the batter.
Fill your copper molds 3/4 of the way with batter and carefully place them on top of the hot sheet pan in the oven. Bake for 15 minutes and then turn the temperature down to 375°F.
Bake for another 35-50 minutes. You can peek at the tops to see if they're done but use your nose - they should smell deeply caramelized, not burnt. The tops will be dark golden brown and slightly lighter in the middle.
When done, remove tins from oven and quickly turn them each onto a wire rack, removing the pastries from the tins. Let canelés rest for 1-2 hours to let the crust harden.