Grease and line three 23 cm (9 inch) springform pans with parchment paper.
In a bowl, combine the flour, baking powder, and salt.
In another bowl, beat the eggs, sugar, and vanilla with an electrical whisk for approximately 10 minutes, or until mixture is pale yellow, triples in volume, and forms a ribbon.
Slowly add the hazelnut butter, all while whisking constantly.
Set the whisk to low and add the dry ingredients, alternating with the milk or buttermilk, until batter is smooth.
Divide the batter between the pans.
Bake in the oven approximately 45 minutes, or until a toothpick inserted in the centre comes out clean.
Mascarpone frosting :
Whisk together all the ingredients until soft peaks form.
Set aside.
Maple-cranberry compote :
In a small saucepan, combine the cranberries, sugar, and cornstarch.
Add the maple syrup and bring to a boil.
Let stew for 5 minutes.
Remove from heat, add the rosemary.
Let cool completely before using.
Assembly :
Slice each cake in half horizontally.
Using a pastry brush, soak each layer with maple syrup.
Spread a thin layer of mascarpone frosting on the first cake layer.
Cover with a layer of cranberry compote, leaving approximately 2.5 cm (1 inch) of empty space around the outer perimeter.
Stack the next cake layer and repeat.
Apply a thin layer of the mascarpone frosting all over the cake, letting parts of the cake peak through.
Decorate with frosted cranberries and fir branches if desired.