This is traditionally eaten around Epiphany in France, where you can get it in all bakeries. A small porcelaine figure (the 'fève') is placed in the frangipane and the person who gets it becomes king and wears a paper crown
1 pound puff pastry
4 ounces ground almonds
4 ounces icing sugar
4 ounces butter at room temperature
4 large eggs
2 oz flour
1 tablespoon dark rum
1/4 cup slivered almonds
1 fève (optional)
For the filling: Combine the ground almonds, sugar and butter until smooth.
Add three of the eggs, flour and rum: mix until combined.
Stir in slivered almonds.
Preheat oven 375°F (190°C).
To assemble, divide the dough into two equal parts.
Roll out one part to form a 10 inch circle and place on a baking sheet.
Spread the filling on the pastry leaving a rim, about half an inch wide, all the way around. Put in a porcelaine figure (feve) if you have one. Brush the rim with egg.
Roll out the rest of the dough to form a 9 inch circle. Place on top of the filling.
Pinch together the pastry at the edges, making sure that it is well sealed. Brush the top with the remaining egg. Make a few slits in the center of the pastry.
Bake in preheated oven for about 30 minutes.