Gateau Invisible (Invisible French Apple Cake)

Please watch the video for the instructions.
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RECIPE
Crumbles:
80 g all-purpose flour
40 g unsalted butter melted
30 g brown sugar
½ tsp ground cinnamon
Cake batter:
800 g apples before peeling (about 4-5 large apples)
100 g eggs (room temperature) weight doesn't include shell, 2 large eggs
50 g brown sugar
30 g melted butter unsalted
100 g milk
1 tsp vanilla extract
100 g all-purpose flour
1 tsp baking powder
⅛ tsp salt
1 tsp ground cinnamon
¼ tsp ground nutmeg