Preheat oven to 170°C (350°F). Place the butter, caster sugar, brown sugar and vanilla in an electric mixer and beat for 2 minutes. Add the eggs, one at a time, beating well after each addition until combined. Add the flour, cocoa, bicarbonate of soda and baking powder and mix until just combined. Fold through the chocolate and coconut until combined. Roll 50 x tablespoonfuls of the cookie dough into balls and place on lightly greased baking trays lined with non-stick baking paper, leaving room to spread. Reserving remaining cookie dough. Flatten slightly and bake for 10–12 minutes or until doubled in size. Allow to cool on trays for 10 minutes before transferring to wire racks to cool completely.
Roll teaspoonfuls of the remaining dough and place on lightly greased baking trays lined with non-stick baking paper, leaving room to spread. Flatten slightly. Bake for 6 minutes or until doubled in size. Allow to cool on trays for 10 minutes before transferring to wire racks to cool completely. Place in an airtight container until ready to use.
Place the cream, sour cream, vanilla and icing sugar in a bowl and whisk until stiff peaks form. To assemble, arrange the large cookies in the base of lightly greased 20cm-round, deep-sided loose-bottomed cake tin lined with non-stick baking paper. Top with 1 cup (250ml) of the cream mixture and spread over the cookies. Repeat with the remaining large cookies and cream mixture, finishing with a layer of the cream+. Cover with plastic wrap and top with a baking tray. Place canned vegetables on the tray to weigh down and refrigerate overnight or until set++. Place a cake stand on the cake and carefully invert. Gently slide the tin from the cake. Using a palette knife, spread the cake with the whipped cream and lightly press the small cookies into the top and sides of the cake. Serves 8–12.