MAKE CAKE LAYERS
Preheat oven to 350. Spray 12 - 9 inch cake pans well with bakers spray. I used foil pans as I don't have 12 cake pans
Seperate eggs. Put yolks in 1 large bowl and whites in another large bowl. Let stand, covered to come to room temperature, at least 30 minutes
Whisk flour, baking soda and salt in bowl, set aside
Beat egg yolks with buttermilk, 2 cups of the sugar and vanilla until light and increased in volume, 5 to 8 minutes. Beat in reserved flour mixture just until well blended
With clean, dry beaters, beat egg whites and cream of tarter until foamy and increased in volume
Gradually add remaing 1/4 cup sugar until glossy firm peaks form
Add 1/4 of egg white mixture to yolk mixture and fold in. Add remaining whites to yolks in 3 more additions, folding each addition in being careful not to deflate but thoroughly blending in
Evenly divide batter in the 12 prepared pans. I used a one cup measure to scoop and pour into each pan, tapping pans to level batter
Bake 4 cakes at a time in preheated oven until light golden, and cake feels dry not sticky. A toothpick will be mostly clean. About 7 to 9 minutes. Cool pans on racks 5 minutes then run a small sharp knife around edges to prevent any sticking
MAKE FILLING. Whip cold Chocolate Ganache, recipe attached below
On a serving plate starting with one cake frost each layer with a thin layer of chocolate ganache, sandwichng each layer. Keep top layer un frosted, and chill cake 2 hours to firm up before glazing.
MAKE CHOCOLATE GLAZE
Place semi sweet chocolate on large bowl. Heat cream to a simmer, either stove top or in microwave. Pour over chocolate, let sit undisturbed 1 minute to melt chocolte. Whisk until smooth. Let glaze sit at room temperature until it thickens some but is still able to pour
Glaze cake by spooning glaze over top of cake and letting it slide down sides
Garnish with sprinkles while glaze is wet to allow to stick. Chill cake to set before cutting.