Prepare the apple: Peel and core the apple. Cut it into 4 slices, then dice into even pieces about 1/2 inch (1 cm) in size.

Cook the apple: In a small saucepan, melt 1 teaspoon of butter over low heat. Once melted, add 2 teaspoons of light brown sugar and 1/2 teaspoon of ground cinnamon, then stir to combine. Cook uncovered over low heat, stirring regularly. When the mixture starts to caramelize, add the diced apple and stir. Continue to cook uncovered over low heat, stirring regularly, until the apple pieces are soft.

Prepare the croissant: Slice the croissant open with a bread knife. Place the croissant in an oven at 250°F (120°C) until it is warm and the surface is slightly crisp. Fill the croissant with the warm apple mixture. Serve ideally with a hot beverage.