Line a 9-inch (23-cm) cake pan with waxed paper; grease paper.
Preheat oven to 300°F (150°C).
To make cake, beat butter, sugar, vanilla, salt and rum in a large bowl until pale and creamy.
Beat in eggs one at a time.
If mixture curdles, add 1 tablespoon flour.
Sift remaining flour with baking powder; mix with raisins, ground almonds and can died peel.
Fold flour mixture gradually into egg mixture.
Turn batter into prepared pan; smooth the surface with the back of a wet spoon.
Arrange almond halves in a circular pattern on top.
Bake 4-1/4 to 4-3/4 hours or until a skewer inserted in center comes out clean.
Leave cake in pan about 15 minutes then turn out onto a rack to cool.
Remove lining paper when cake is completely cool.
To make glaze, heat sugar and water in a small saucepan, stirring constantly until sugar is completely dissolved.
Boil 2 to 3 minutes.
Cover top of cake with glaze; let cool.
To make decoration, warm jam and brush over sides of cake.
Measure circumference of cake with a piece of string.
On a surface sprinkled lightly with powdered sugar, roll three-fourths of almond paste into a long rope the length of the string.
Flatten with a rolling pin to 1/2 inch (2 cm) more than height of cake.
Trim almond paste; cut 1/2-inch (2-cm) strips along top edge as illustrated.
Press strip of almond paste firmly onto sides of cake.
Knead food coloring into remaining almond paste.
Cut out small Christmas trees; attach to cake with unbeaten egg white.