Preheat the oven to 180°C (350°F/Gas 4). Grease ten 13 cm (5 inch) flan tins (tart pans).
For the sponge cake, melt the chocolate in a heatproof bowl set over a saucepan of barely simmering water. Cool to room temperature.
Using an electric mixer, beat the butter and sugar until light and creamy. Add the egg yolks one by one, beating after each addition until light and fluffy. Mix in the almond meal, chocolate and cayenne pepper.
Beat the egg whites with the salt until stiff. Fold the beaten egg whites and the flour into the chocolate mixture. Divide the mixture evenly among the prepared tins and smooth the surface. Bake in the centre of the oven for about 25 minutes, then remove from the oven and leave to cool in the tins on a wire rack.
Remove the chili stalks. Remove the seeds (or if you prefer more heat, leave them in). Chop the chillies finely.
Roast the chillies and the pumpkin seeds in a dry frying pan. Add the brown sugar and stir over low heat until melted. Pour the mixture onto a plate, separating the seeds as much as possible, and leave to cool. If the seeds stick to each other, separate them by hand.
Chop the chocolate finely and melt in a heatproof bowl set over a saucepan of barely simmering water. Chop the butter into small pieces. Add to the chocolate and stir to melt.
Remove the tartlets from the tins and coat with the chocolate mixture. Sprinkle immediately with the pumpkin seeds, and leave to harden.