In a large bowl combine flour, both sugars, cocoa, baking powder, baking soda and salt. Set aside.
With a stand mixer with the paddle attachment, add in milk, oil, eggs and vanilla until combined.
Slowly add the dry ingredients to the wet ingredients with the mixer on low.
Pour in the hot coffee (Batter will be thin). Beat on high speed for 1 minute to add air to the batter and to get out any clumps.
Divide between the prepared pans and bake for 23-25 minutes or until a toothpick inserted in the center comes out clean.
Cool the cake completely before frosting.
When you are ready to assemble the cake place 1 layer of the chocolate cake on a cake platter or serving plate. Top with some of the salted caramel buttercream and spread to the edges of the cake.
Place the remaining cake layer on top and frost the whole cake.
Drizzle with chocolate ganache and place in the fridge to set for 30 minutes then enjoy!
Salted Caramel Sauce
Add all of the ingredients except for the vanilla and salt to a saucepan. Cook over low-medium heat until thickened stirring occasionally. About 8 minutes. If the sauce isn't getting a lot thicker turn up the heat a bit and keep and eye on it making sure to whisk constantly. (The sauce will thicken as it cools in the refrigerator).
Stir in vanilla and salt.
Take off the heat and allow to cool in the saucepan. Transfer to a container and place in the refrigerator to firm up and cool.
Salted Caramel Buttercream
Add egg whites and brown sugar to a stand mixer with the whisk attachment. Whisk until combined.
Place the bowl from the stand mixer over a hot water bath and whisk constantly until the mixture is no longer grainy and the sugar is dissolved, about 5 minutes.
Place the bowl of the stand mixer back and whip on med-high until it is stiff and cooled, about 5 minutes.
Switch to the paddle attachment. Slowly add cubed butter and mix until smooth.
Pour in caramel sauce and beat until combined. Set aside until you are ready to frost your cake.