Preheat the oven to 350°F.
MAKE THE HONEY BUTTER
In a medium bowl, add the hot melted butter, honey, brown sugar, vanilla extract, and salt.
Whisk well until smooth, glossy, and fully combined.
ASSEMBLE AND BAKE
Dip the cut side of each croissant half into the honey butter mixture, coating it evenly.
Place each croissant half cut side down directly onto a non-stick baking sheet.
Once all the croissants are on the tray, use a pastry brush to lightly brush a little more of the honey butter around each one. Don't put a lot or it will be too sweet.
Bake for 15 to 18 minutes, until deeply golden and caramelized on the cut side.
Once out of the oven, the butter and sugar will have spread across the tray and will be very hot. Carefully handle each croissant and gently swirl it around in the melted mixture to separate it from the tray and pick up a bit more of the caramelized coating.
Let cool cut side down on the tray for 10 to 15 minutes to allow the coating to firm up before removing and enjoying.