Preheat your oven to 350 degrees F. Spray three 8 inch or four 6 inch round cake pans with non-stick spray, place parchment rounds in each pan and spray again. Set aside.

In a small bowl, stir together 3/4 cup brown sugar and 2 teaspoons ground cinnamon. Set aside.

In a large bowl, mix together flour, baking powder, salt and additional cinnamon. Set aside.

In the bowl of a stand mixer, fitted with the paddle attachment, beat the butter and granulated sugar on medium speed until light and fluffy, about 2 minutes.

Add eggs, one at a time, beating well and scraping down the sides of the bowl after each addition. Add vanilla.

With the mixer on medium-low speed, add the flour and buttermilk alternately, starting and ending with the flour mixture and scraping the bowl as needed. Pour about 10 oz. of the batter in each 8-inch pan or 8 ounces in each 6-inch pans. Divide the cinnamon and brown sugar mixture between the cakes (about 2 to 3 oz.), sprinkling evenly over the batter, then top with the remaining batter (about 10 oz. more per 8-inch pan or 8 oz in each 6-inch pan).

Bake for 28 to 30 minutes or until a toothpick inserted in the center of the cake comes out with just a few moist crumbs. Remember, not all ovens are the same, so check your cakes around 25 minutes and keep an eye on them.

Remove cakes from the oven and let cool in pans for about 10 minutes before inverting onto a wire rack to cool completely.

Once cooled completely, wrap each cake layer with plastic wrap and chill for at least 30 minutes. Can be made ahead of time and frozen for up to two weeks. Let thaw for an hour before stacking and decorating. 

In the bowl of an electric mixer fitted with the paddle attachment, beat the butter until light and fluffy, about 2 minutes. 

With the mixer on low speed, gradually add the powdered sugar. When it's all combined, add the heavy, cinnamon and vanilla. Turn the mixer to medium-high speed and beat for about 5 minutes.  

Using a wooden spoon, beat frosting to get air bubbles out.

Place the cinnamon chips and cream in a microwave safe bowl. Heat in the microwave in 15 second intervals, stirring in between, until the mixture is smooth. Let cool to room temperature using on the cake.

After leveling the cake layers (if needed), place one cake layer, top-side up on a cake board or cake plate.

Evenly spread about 1/2 to 2/3 cup frosting over the cake layer.

Pipe a rim of frosting around the edge of the cake layer. Spread about 1/3 cup of the cinnamon chip ganache on the frosting before placing another cake layer on top.

Repeat steps 2 and 3. 

Apply a thin coat of frosting around the entire cake to create a crumb coat. Chill the crumb coat in the freezer for 10 minutes to lock in crumbs.

After the crumb coat is chilled, continue frosting the cake and use the remaining cinnamon chip ganache for a drip.