Preheat the oven to 300°F. Set the oven rack in the middle position.
Soak the currants in cool water for 30 minutes to rehydrate. Drain and set aside.
Prepare the cake pan: Line the bottom of an 8-inch round pan with parchment and butter the sides.
Combine dry ingredients: In a medium bowl, whisk together the flour, baking powder, and salt.
Mix wet ingredients: In a large bowl, beat butter until light and fluffy. Gradually add sugar and then the eggs one at a time. Sift in almond flour and gently fold.
Combine everything: Add the flour mixture, mixed peel, and currants. Fold gently until fully incorporated without overmixing.
Bake the cake: Pour the batter into the prepared pan, smooth the top, and bake for 1 hour or until a skewer inserted comes out clean. Cool in the pan for 15 minutes, then fully on a rack for at least 2 hours.
Make almond paste: Mix almond flour and sugar in a medium bowl. Add 1 egg and stir until smooth. Divide into thirds—combine ⅔ into a disk and wrap in cling film. Form the remaining ⅓ into small balls. Chill for 1 hour.
Roll and top: Roll out the large disk between parchment to 8–9 inches wide and ¼ inch thick. Trim to size and place on top of cooled cake. Score with a skewer or decorate the edges if desired. Arrange the 11 almond paste balls in a ring on top.
Broil to finish: Brush with egg white and dust with sugar. Broil on a lined baking sheet for 2–4 minutes or until golden. Rotate for even browning. Watch carefully to avoid burning.
Garnish and serve: Optionally decorate with candied fruit or other sweets before serving.