• Lightly spray two 9" round cake pans with cooking spray. Use your pans to trace two 9" circles on parchment paper and cut them out. Place inside your cake pans. This will make removing your cakes a lot easier!
• Preheat oven to 325º F.
• Chop chocolate into pieces the size of chocolate chips and put into a medium bowl.
• Pour hot water over chocolate and let sit 2 minutes, chocolate should be completely melted.
• Stir until all melted chocolate is incorporated into the water. Set aside.
• In bowl of stand mixer (if you don't have one, just use your regular bowl and hand mixer), Whip eggs with whisk attachment about 3 minutes until frothy.
• Add canola oil, buttermilk, and vanilla and mix briefly to combine.
• Add flour, cocoa powder, sugar, xanthan gum (if needed) baking soda, baking powder, and salt and mix on medium speed using paddle attachment for 3 minutes.
• Add chocolate mixture and mix until smooth.
• Divide batter evenly between the two pans, about ⅔ full.
• Bake cake for 30-40 minutes, just until a toothpick inserted in the center comes out clean.
• Let cake cool for 20 minutes in the pan before inverting onto cooling racks. Peel the parchment paper off the cakes and let cool completely.

TO MAKE THE FILLING:

• Measure ¼ cup gluten free flour into a medium saucepan.
• Gradually add milk, whisking as you go, until mixture is smooth.
• Heat over medium-low heat, stirring constantly, until mixture is thick like a roux. After about five minutes It should be like a really thick, sticky pudding. Add vanilla.
• Scrape mixture into a bowl, cover with plastic wrap, and refrigerate until cool.
• Meanwhile, in bowl of stand mixer beat butter and granulated sugar with whisk attachment about 8 minutes until smooth and very fluffy. Add milk/flour mixture and whisk another 5 minutes on high, scraping sides often, until it is no longer grainy. It should be creamy and fairly light.
• Slice the mounded top off the cakes, so they are flat. and place one on a rack over a wax paper or foil-lined cookie sheet.
• Spread filling evenly over this cake, and top with the other cake. Press down gently.

MAKE THE GANACHE:

• Put chocolate chips in a medium bowl.
• Heat cream and butter over medium heat just until boiling. Be careful not to scorch.
• Pour cream over chocolate chips and let sit for a few minutes.
• Stir together until mixture resembles a thick chocolate sauce.
• Slowly pour ganache right over your cake. It will spread over the cake as you pour, but you may have to smooth it out a little with a spatula so the ganache runs down the sides.
• Cool in the fridge until the ganache is set. This cake is best if you let it sit in the fridge overnight.
• When ganache is set, you can remove the cake to a serving platter, slice and serve.
• Store leftovers (if there are any!) in the fridge.