For the ice cream: Preheat the oven to 350 degrees F. Brush 1 baking sheet with almond oil; set aside. Place the almonds on another baking sheet and toast them until light golden brown, 5 to 7 minutes. In a medium, heavy-bottomed saucepan, combine 1 1/2 cups sugar and 1/2 cup water and cook over medium-high heat, without stirring, until a medium amber color. Remove the caramel from the heat, immediately add the almonds and stir quickly to thoroughly combine. Turn out onto the prepared baking sheet, spreading quickly to an even thickness. Allow the brittle to cool completely. Coarsely chop and reserve. Heat the milk, cream and 1/2 cup sugar in a medium saucepan until the sugar dissolves and the milk starts to simmer. Add the cocoa powder and chocolate and whisk until smooth. Place the egg yolks and the remaining 1/4 cup sugar in the bowl of an electric mixer fitted with the paddle attachment and beat on high speed until pale yellow and ribbons form, 3 to 5 minutes. Remove the bowl from the stand and slowly whisk in the hot chocolate mixture. Pour the egg and chocolate mixture back into the saucepan and cook over medium-low heat, stirring constantly with a wooden spoon, until thickened and the mixture coats the back of the spoon. Do not allow the mixture to boil! Pour the mixture through a fine mesh strain into a bowl set over an ice bath and stir in the coffee liqueur, vanilla and salt. Stir until the mixture is cold. Place a piece of plastic wrap directly on top of the custard and chill completely in the refrigerator, at least 4 and up to 24 hours. Pour the chilled custard into the bowl of an ice cream maker and process according to the manufacturer's directions. Stir in the coarsely chopped almond brittle. Spray a 2 quart glass bowl with cooking spray, line with plastic wrap and spray the plastic wrap. Scrape the ice cream into the bowl and smooth the top. The ice cream will not fill the bowl; you're looking for the larger surface of the ice cream to be about 8 inches in diameter. Press more plastic wrap over the top and freeze until solid, at least 4 hours. For the cake: Preheat the oven to 325 degrees F. Butter 1 (9-inch cake) pan and line the bottom with parchment paper. Whisk together the flour, baking powder, baking soda and salt in a medium bowl. Melt the butter in a medium saucepan over medium heat. Whisk in the cocoa powder and cook for 1 minute. Remove from the heat, add the sugars and whisk until dissolved. Add the coffee, buttermilk, eggs and vanilla extract and continue whisking until smooth. Scrape the batter into the prepared pan and bake on the middle rack until a toothpick inserted into the center comes out with a few moist crumbs attached, 35 to 40 minutes. Let cool in the pans on a baking rack for 20 minutes. For the meringue: Preheat the oven to 500 degrees F. Fill a medium saucepan 1/4 full with water. Set the saucepan over medium heat and bring the water to a simmer. Combine the egg whites, sugar and cream of tartar in the heatproof bowl of an electric mixer and place over the saucepan. Whisk constantly until the sugar is dissolved and the whites are warm to the touch, about 3 minutes. Transfer the bowl to the electric mixer fitted with the whisk attachment and, starting on low speed and gradually increasing to high speed, whip until stiff, glossy peaks form, about 10 minutes. Add the vanilla and almond extracts and the chocolate and mix until combined. Immediately fill a pastry bag, fitted with a #5 star tip, with the meringue.
To assemble: Unmold the ice cream onto the cake and pipe the meringue onto the ice cream in a decorative fashion (or spoon the meringue over the ice cream and swirl with a rubber spatula). If the ice cream starts to soften, return the cake to the freezer for 15 minutes. Place in the oven and bake until the meringue just starts to brown, 1 to 2 minutes. Remove from the oven and serve immediately.