Giant Ferrero Rocher Hazelnut Mousse Cakes

INGREDIENTS

6 oz

butter (at room temperature)

4 3/4 oz

granulated sugar ((2/3 cup))

5 oz

brown sugar ((2/3 cup packed))

eggs (at room temperature)

2 tsp

vanilla extract

8 oz

buttermilk (at room temperature, (1 cup))

4 oz

sour cream (at room temperature, (1/2 cup))

2 tbsp

water or brewed coffee

7 4/5 oz

all-purpose flour ((1¾ cups))

3 oz

sifted unsweetened cocoa powder ((1 cup))

1 1/2 tsp

baking soda

1/2 tsp

salt

lbs chocolate candy coating

4 oz

toasted and skinned hazelnuts (coarsely chopped, about 1 cup)

" spherical chocolate molds (can substitute spherical cake pans instead)

9 oz

semi-sweet chocolate

12 oz

heavy cream (divided use)

11 oz

Nutella chocolate-hazelnut spread ((1 cup))

salt

1 tsp

unflavored powdered gelatin ((2 1/2 packets))

3 tbsp

water

2 oz

toasted and chopped hazelnuts ((1/2 cup))