Combine the heavy whipping cream, condensed milk, powdered sugar, extracts and cardamom in the bowl of a stand mixer, fitted with the whisk attachment. Alternatively, you can use an electric hand mixer. Whip on high speed until soft peaks form, about 2–5 minutes depending on the type of mixer you're using. Set aside.
Line an 8 ½ x 4 ½-inch loaf pan with plastic wrap, making sure to have a couple inches of overhanging for easier removal of the frozen cake. Spread ¼-inch layer of the whipped cream mixture onto the bottom of the loaf pan.
Split the graham crackers along the lines into quarters. Line the loaf pan with the split graham crackers, arranging the rectangles vertically. Spread a layer of cream on each cracker and layer them lengthwise. Continue to sandwich the crackers and cream tightly until no space remains in the pan. Cover the top with another ¼-inch layer of cream, completely covering the crackers. Wrap the whole loaf with another layer of plastic wrap and freeze the cake overnight.
For the chocolate ganache & marshmallow fluff
An hour before assembling the cake, prepare the chocolate ganache. Place the chopped chocolate in a medium bowl. Bring the heavy cream to a boil and pour the hot cream over the chocolate. Let sit for a few minutes and then stir until the chocolate is fully melted. Stir in the butter and then allow to cool to room temperature.
Remove the ice box cake from the freeze, unwrap the outer layer of plastic wrap and invert the cake onto a wire rack-lined baking sheet. Remove the second layer of plastic wrap. Carefully pour the room temperature ganache over the ice box cake, coating it completely. Place in the freezer for another hour to allow the ganache to set.
While the ganache-enrobed cake is chilling, prepare the saffron marshmallow fluff. Microwave the almon extract for 10–20 seconds, add the saffron and let steep while you make the fluff. Combine the egg whites, sugar and cream of tartar in a heatproof mixing bowl. Place the bowl over a small saucepan of simmering water, making sure the bottom of the bowl does not touch the water.
Whisk the egg white and sugar mixture continuously until the sugar has dissolved completely and the mixture has reached 160°F. Transfer the mixture to the bowl of a stand mixer, fitted with the whisk attachment. Alternatively, you can use an electric hand mixer. Whip on high speed until it reaches stiff, glossy peaks, about 5–10 minutes depending on the type of mixer you're using. Fold in the reserved almond extract saffron mixture.
To finish the cake
Remove the ice box cake from the freeze and transfer onto a serving platter. Mound the saffron fluff on top of the cake, using an offset spatula or knife to create peaks. Serve immediately. Serving tip for clean pieces: slice with a warm, dry knife (run knife under hot water and then wipe dry).