Preheat the oven to 350 In a large bowl, whisk together, flour, cocoa, sugar baking powder, baking soda and salt.
In a medium bowl, whisk the eggs, milk, oil and vanilla. Pour the wet ingredients into the dry and mix just until combined. Add the boiling water and stir until combined - the batter will be fairly thin. Pour the mixture into a 9" x 13" baking pan coated with nonstick spray.
Bake until a toothpick placed near the center of the cake comes out mostly clean with a couple moist crumbs attached, about 40 to 50 minutes. Remove from the oven and let cool completely. Turn the cake out of pan and place the cake, top side up, on a wire rack.
To make the filling Reduce the oven temperature to 325 On a large piece of parchment, trace a rough 9" x 13" rectangle onto the paper and place it on a large baking sheet.
Add the almonds and confectioners' sugar into the bowl of a food processor - pulse until they’re finely ground.
In a medium mixing bowl, beat the egg whites at medium speed until soft peaks form. Add the granulated sugar and beat until the whites are stiff and glossy, about 2 minutes. Gently fold in the ground almond mixture. Scoop the meringue onto the parchment paper and use an offset spatula to fill out the outline you traced on the paper. Scatter the chopped peanuts on top. Bake until lightly browned and firm, about 15 to 20 minutes. Remove from the oven and let cool.
In a medium bowl set over a saucepan of simmering water, heat the peanut butter with the butter and milk chocolate, stirring constantly, until smooth and melted. Remove from the heat and fold in the Rice Krispies. Spread the mixture all over the meringue rectangle. Place in the freezer and let harden.
To make the ganache In a medium bowl set in a saucepan of simmering water, melt the chocolate. Whisk in the cream until smooth. Remove from the heat and place the bowl into the refrigerate for 1 to 1 1/2 hours, whisking occasionally, until thick enough to spread.
To assemble the cake Using a serrated knife, carefully slice the cake horizontally in half.
Place the bottom cake layer, cut side up, on a large board. Spread about one-third of the ganache over the cake. Invert the filling onto the cake and peel off the parchment paper. Spread half of the remaining ganache over the filling, then top with the second cake layer. Refrigerate until firm, at least 1 hour. Using a serrated knife, trim the edges. Spread the remaining ganache over the top and sides of the cake and refrigerate to set.
