Preheat the oven to 180°C. Peel the apples, cut them into cubes and lightly caramelise them in a pan with 20g of sugar. When the apples begin to colour, remove them from the heat and let them cool to room temperature.
In a bowl, combine the eggs and the remaining sugar. Whisk until the mixture is frothy and clear. Add the flour, milk and cinnamon, then mix until the batter is smooth. If there are any lumps, strain them out using a fine sieve.
Generously butter a tart pan and place the caramelised apples in it. Pour in the batter and bake for 40 minutes at 180°C. Remove from oven and let cool.
Is the texture of your flognarde somewhere between that of a flan and a cake? If so, congratulations – it’s a success! Serve this dessert slightly warm or cool.
For an elegant presentation, cut out flognarde circles of the same size and decorate them with julienne-cut apples. Top each portion with a cinnamon stick.