Preheat the oven to 390°F (200°C) and prepare a non-spill baking sheet (no need to grease it). Alternatively, use a silicone baking mat or a 12 x 16 inches (30 x 40 cm) baking sheet lined with parchment paper. Grease the baking tray, then add the parchment paper and lightly grease it.

To make the cake batter, use a hand whisk to mix ground almonds, all-purpose flour, and icing sugar in a clean mixing bowl.

Melt the butter in the microwave at 20-second increments and set aside.

Place whole eggs in the bowl of a stand mixer fitted with a whisk attachment and whisk for a few seconds. Add dry ingredients and mix at medium speed for 2-3 minutes until homogeneous. Pour the cooled melted butter and gently mix with a spatula.

In a separate clean bowl, whip egg whites at high speed using an electric mixer. Once frothy, gradually add caster sugar and beat until stiff peaks.

Gently fold the beaten egg whites into the almond mixture in two or three additions using a rubber spatula.

Pour the sponge batter onto the baking sheet and smooth the surface with a long offset spatula or a flat knife.

Bake the Joconde biscuit for 10 to 15 minutes. If using a silicone mold, place it on the oven rack. The sponge should be slightly golden and not stick to your finger.

Remove the cake from the oven. Flip it onto powdered sugared parchment paper or a kitchen towel sprinkled with icing sugar. Gently peel the baking mat or parchment paper.

For a cake roll, sprinkle it with icing sugar and roll the cake into the towel for 10 minutes. Then, unroll it and let it cool to room temperature. For an entremets dessert, let the Joconde sponge cool to room temperature, then cut into necessary sizes.