Preheat oven to 350 F (180 C). Grease two 9-in. (23-cm) round baking pans, line bottoms with parchment paper. Melt chocolate in double-boiler. Set aside to cool.
In bowl, whisk together flour, cocoa, baking powder, baking soda and salt. In another bowl, combine buttermilk and 18% cream. Set aside.
In large bowl, using hand-mixer, beat butter until fluffy. Gradually beat in 1 3/4 cups (425 mL) sugar, then the eggs one by one. Beat in vanilla and melted chocolate. In one-third portions, beat the dry ingredients into butter mixture, alternating with buttermilk mixture, and finishing with dry ingredients. Scrape down sides of bowl as needed.
Divide batter between the 2 cake pans, spreading batter evenly. Bake approx. 40 min, or until cake springs back when lightly pressed and toothpick inserted into centre comes out clean. Cool completely.
Meanwhile, make cranberry filling by combining cranberries, 1/2 cup (125 mL) water and remaining 1 3/4 cup (425 mL) sugar in saucepan. Cover and bring to boil. Cook, stirring occasionally, until cranberries pop and mixture thickens (for 2 cups/ 500 mL filling). Set aside to cool completely.
Remove cakes from pans and discard parchment. Trim edges, if required, to straighten sides. Cut cakes in half horizontally. In large bowl, whip 35% cream and icing sugar. Place first cake layer onto serving plate, spread with 1/3 cranberry filling then approx. 1/5 whipped cream mixture. Repeat with second and third cake layers. Place fourth cake layer on top and spread with thicker layer of remaining whipped cream. Garnish with chocolate shavings.