Preheat oven to 350 degrees F. Prepare three 8-inch round cake pans (or four 6-inch round cake pans) with nonstick spray, parchment paper and another coat of spray on the parchment. Set aside.

In bowl of electric mixer, combine all the dry ingredients.

In a separate bowl, add all remaining wet ingredients and mix briefly. With the mixer on low speed, add the wet ingredients to bowl with dry ingredients and mix with the paddle attachment until combined. Scrape down the sides of the bowl and mix again on low for about 20 seconds.

Divide batter among cake pans (about 15 to 16 ounces of batter in each 8-inch cake pan or 11 to 12 ounces of batter in each of the four 6-inch cake pans), using a scale to weigh each pan for even layers. Batter will be thin.

Bake for 18 to 20 minutes. Cakes are done when toothpick comes out with a few moist crumbs on it.

Cool on wire racks for 15 minutes then gently invert onto racks until cooled completely. Level if needed. 

Can be wrapped in plastic wrap and stored in your freezer for up to a week. For longer storage, wrap the layers in tin foil and place inside a large zip lock bag.

Combine the butter and Nutella and beat on medium-high speed for 2-3 minutes.

With the mixer on low speed, add the sifted powdered sugar, a little at a time until incorporated. Beat for another 2-3 minutes.

Add remaining ingredients and beat for another two minutes, until light and fluffy.

Use a wooden spoon to beat frosting for a few minutes to get rid of air pockets.

Best used right away. 

Using chilled cakes, place the first cake layer on a cake plate or stand, right side up.

Spread about three tablespoons of Nutella across the top of the cake.

Spread about 1/2-3/4 cup of the Nutella frosting on top of the Nutella. Place strawberry slices on top of the frosting and push down slightly so the strawberries are secure.

Repeat step #2 and #3 for another layer.

Place final cake layer on top of the second layer of strawberries, bottom side up.

Frost the cake with a thin coat of frosting to lock in the crumbs. Freeze the cake for 10 minutes to set the crumb coat.

Continue to decorate with remaining frosting. If the remaining frosting is a little stiff at this point, add another tablespoon of sour cream or heavy cream and beat again for two minutes.