Heat the oven to 170 C / 340 F. Butter a 20 cm / 8-inch round cake pan and line the base with parchment.
Cream the butter and sugar together with a hand mixer until pale and fluffy, about 3 minutes.
Add the eggs one at a time, beating well after each addition until fully combined.
Stir in the almond flour, then fold in the all-purpose flour, baking powder, and salt until just combined.
Fold in 40 ml dark rum and the vanilla extract until the batter is smooth and even.
Pour the batter into the prepared pan and smooth the top with a spatula.
Bake for 35 to 40 minutes, until a skewer inserted in the center comes out clean and the top is deep golden.
Cool the cake in the pan for 10 minutes, then turn it out onto a wire rack.
While the cake is still warm, whisk the powdered sugar and 30 ml rum together until smooth and pourable.
Brush or pour the glaze over the warm cake so it soaks into the top. Let set for 15 minutes before slicing.
