Cut a round of parchment for the bottom and wide strips for the sides of the pan. Using softened butter, grease an 8-inch (20 cm) round cake pan and line it with parchment paper. Alternatively, you can flour it with all-purpose flour instead of using baking paper. 

Preheat the oven to 355°F (180°C). To make the cake batter, sift almond flour in a clean bowl and set aside. Then, using a flour sifter, sift all-purpose flour in a separate bowl. In a large mixing bowl, place softened butter and icing (powdered) sugar and whisk with an electric mixer until the mixture becomes creamy and homogeneous. 

Add the sifted almond powder and whisk the mixture well. Then, add eggs, one at a time, whisking the mixture well between each addition. Pour the sifted flour and mix the batter with a rubber spatula. Add rum or another flavor of your choice and mix.

Pour the cake batter mixture into the prepared pan, smooth the surface, and bake the cake for 40-45 minutes. Cover the cake with aluminum foil if the cake browns quickly. Check the cake for doneness by testing it with a toothpick in the center.

Remove the cake from the oven. Cover the pan with a wire rack and flip it over to gently unmold the cake: it will be upside down. Soak the bottom of the cake (it will be the top now) with rum using a pastry or silicone brush. Let it cool to room temperature.

To make the glaze, sift the icing sugar in a small bowl and add white rum little by little, beating with a fork. Do not add the rum all at once: add it gradually to control the texture of the frosting.

Pour a small amount of the glaze into the center of the cold cake and spread it towards the edges. Use the back of a tablespoon or an offset spatula. Add more glaze and smooth it. If the icing start dripping, catch it with your finger by running along the cake's edge. Work with icing quickly since it hardens fast.