Preheat the oven to 180°C (350°F), conventional oven.
Start by greasing the cake pan. If using a removable cake ring, line it with a round of parchment paper about 1 cm (½ inch) larger so it comes slightly up the sides. Grease the parchment paper, then secure the outside of the ring with a sheet of aluminum foil, folding it tightly all around to prevent any leakage.
Melt the butter and let it cool slightly.
In a mixing bowl, whisk the eggs and sugar without trying to lighten the mixture or make it double in volume. Whisk just enough to dissolve the sugar and lightly foam the mixture.
Add the almond flour and mix with the whisk, then add the melted butter and a small splash of bitter almond extract (1 teaspoon). I use the brand La Patelière, which is easy to find in supermarkets.
Mix well, then pour the batter into the prepared pan.
Level the surface by gently tapping the pan on the counter, then cover the entire top with sliced almonds.
Bake for 30 to 35 minutes, depending on your oven, until the cake is nicely golden and a skewer inserted into the center comes out clean.
Unmold onto a wire rack and let cool completely.
Once cooled, dust with powdered sugar if desired, though this step is optional.