Beat together unsalted butter and superfine sugar until creamy and combined. Add in the egg and mix until fully integrated.

Gradually incorporate all-purpose flour, baking powder, and lemon zest until a soft dough forms.

Wrap the dough in plastic wrap and refrigerate for at least 30 minutes.

Process raw almonds and dark chocolate in a food processor until they form coarse crumbs.

Heat whole milk in a saucepan until warm, then stir in the processed mixture, sugar, cocoa powder, rum, and cinnamon.

Allow to cool slightly, then whisk in an egg yolk.

In a clean bowl, whip egg whites until stiff peaks form, then gently fold into the chocolate almond mixture.

Roll out chilled dough and cut circles to fit mini tart pans. Spoon filling into each shell, cover with smaller circles and seal the edges.

Preheat oven to 350°F (180°C) and bake for 15-18 minutes until golden.

Cool in pans for 10 minutes then transfer to a wire rack and dust with powdered sugar before serving.