If you prepare the crumble ahead of time,
serve it hot. It’s much tastier that way!
In a bowl, combine the corn starch, sugar and eggs using a whisk. Put the milk in a saucepan over medium-high heat. Add the vanilla and heat just to the boiling point. Remove from the heat, add to the first preparation and stir. Transfer the mixture into a saucepan, put back on the heat 4 to 5 minutes and keep boiling while stirring with a wooden spoon to keep the cream from sticking. Remove the vanilla. Pour the mixture into a bowl and let cool about 20 minutes Add the semi-whipped cream and stir well using a whisk to obtain a smooth and uniform cream. Keep in the refrigerator.
Combine the flour, sugar and butter. Add the pecans and rosemary and stir well.
Put a frying pan over high heat with the butter and maple sugar. When they are lightly colored, sauté the apples 5 minutes to color them. Pour into a cooking dish with a depth of at least 5 cm (2 in.) and spread the crumble preparation over top. Put in the oven about
15 minutes at 200ºC (400ºF) until lightly colored.
Pour the mousseline into small serving pots or spread it on individual plates. Cut the crumble up into squares and place on the plates using a spatula.