Nutella, coconut and almond crumble

Thanks to Ho Voglia di Dolce for this easy, extremely indulgent recipe.
INGREDIENTS
180 g '00' flour
80 g ground desiccated coconut
100 g brown sugar
120 g butter
1 teaspoon baking powder
1 yolk
1 pinch salt
FILLING
250 g Nutella
1 bar white chocolate
Flaked almonds
30 g desiccated coconut
Icing sugar
I put flour, brown sugar and coconut in the processor.
I add baking powder.
A pinch salt.
Softened butter pieces and yolk.
I process until crumbly, briefly work on the surface until even without overworking, and divide equally.
I line a 20 x 20 square tin with parchment and flatten half the dough by hand and spoon.
I soften Nutella in bain-marie or microwave and spread on the base.
I break chocolate into squares over Nutella.
I crumble the other dough half evenly over it.
I add 30 g coconut.
I scatter almonds.
I bake at 180°C for about 30/35 minutes, watching browning and covering with foil if needed.
I remove cold and cut squares; I made 9 large ones, but choose smaller if preferred.
I put in paper cases.
I dust lightly with icing sugar. For Nutella lovers, this is an antidepressant rather than a dessert!