Preheat oven to 350 degrees. Grease three 8" pans by spraying (with baking spray or butter) and add a buttered/sprayed wax paper liner to the bottom.

Add flour, sugar, cocoa, baking powder, baking soda, salt, and espresso powder to the bowl of your stand mixer. Thoroughly mix using the paddle attachment until well combined.

Add the milk, Bailey's, vegetable oil, eggs, and vanilla to the flour mixture and mix together on medium speed until well combined. Reduce speed and carefully add the boiling water to the cake batter. Beat on high speed for about 1 minute to add air to the batter. (The batter will be very thin; this is normal.)

Distribute cake batter evenly between the three prepared cake pans. Bake for 30-35 minutes or until a toothpick or cake tester inserted in the center comes out clean.

Remove from the oven and allow to cool for about 10 minutes. Remove from the pan and cool completely. (The cake layers should be frozen or completely cold-refrigerated before assembling your cake.)

Chill the bowl and beaters while making the cake.

Combine the dry pudding mix, heavy cream/whipping cream, and Bailey's in the chilled mixing bowl.

Begin on low speed until everything is well combined. Increase the mixer speed and beat until the mixture is thick.

Refrigerate until ready to use. (You can make this filling up to 5 days in advance. It should be completely chilled before assembling your cake.)

Put the Bailey's in a measuring cup and add enough milk to create 1 cup of liquid.

In a small saucepan, whisk flour into the milk & Bailey's mixture and stir constantly until it thickens. You want it to be very thick -- thicker than a normal cake mix; more like a brownie mix. Remove from heat, cover it and let cool to room temperature. (You can put it in the fridge to cool if you're in a hurry.)

While the mixture is cooling, cream together the butter, vanilla and sugar until light and fluffy, trying to get most of the graininess out of the mixture.

Add the completely cooled flour mixture to the butter/sugar mixture and beat the living daylights out of it. If it looks separated, it's not beaten enough. Beat it on high speed until it resembles whipped cream.

Place first cake layer on pedestal or cake base/plate. Pipe a ring/dam around the edge of the layer, about 1/4 inch from the edge using a piping bag & tip or plastic bag with a corner tip cut away. Then apply the mousse filling within the dam. Repeat for the next layer and then place final cake layer on top.

Frost the cake with a crumb coating, chill to set and then follow up with the final coat of frosting. Pipe decorative border at the bottom of the cake, if desired. Chill again.

While cake is chilling, make the ganache. Add heavy cream and butter in a small saucepan on low heat until the butter has melted and the cream is warm throughout.

Add chocolate chips, espresso powder (or brewed coffee) and salt. Stir constantly over VERY low heat until the chips have melted and the ingredients are thoroughly mixed. Funnel ganache into a squeeze bottle (or put in a zipped plastic bag) and let cool to room temperature.

When your cake is thorough chilled, use the squeeze bottle with 1/8 inch opening cut in the nozzle (or the zipped plastic bag with a 1/8 inch cut in one corner) and squeeze the ganache drips starting on the sides. (If your drips are not flowing very well, zap your ganache 10 seconds at a time until you get the right consistency. If the drips are too runny, your ganache needs to cool a bit longer. This might take some patience and practice to get it "perfect," but it will taste equally as good if it's not.) Then finish off the top by squeezing a solid coat on the top. Use your frosting spatula to smooth out the top. To get a nice glossy finish, run the spatula under hot water to warm it up first.

Tada! You have a beautiful, delicious cake!