These tasty cookies and cream ice cream cake is great for birthdays and makes 1 (9-inch) ice cream cake that will serve 12 people.
For the cookies, beat the butter and icing sugar until smooth, then add the egg yolks all at once and beat until well combined. In a separate bowl, sift the flour, cocoa powder, cornstarch and salt. Add this to the butter mixture and stir until evenly combined. Shape the dough into a log about 2 inches in diameter, wrap and chill until ready to use.
Preheat the oven to 325 ºF (160 ºC) and line 4 baking trays with parchment paper.
On a lightly floured work surface, knead the first dough disc to soften it (so it won’t crack when rolling) divide it in half, and roll out to a circle just over 9-inches (23 cm) across and just under ¼-inch (6 mm) thick. Use the edge of a 9-inch fluted tart tin as a giant cookie cutter and press into the dough to cut it (or you can use a 9-inch/23 cm round cake pan to press and then cut out a circle). Use the bottom portion of the tart tin to slip under the large cookie and slide it onto the baking tray. Set aside the scraps and repeat with the other half of this piece of dough and then the other chilled disc, so that you have a total of 4 large cookies. Roll out the remaining scraps and cut into 4 circles about 4 ½ -inches (11.5 cm) across and place them on the baking trays. Bake the cookies (in batches, if needed) for about 14 minutes, until the surface of the cookie is evenly matte. Let the cookies cool completely on the trays.
To assemble the cookies, lightly dust a work surface with icing sugar, divide the fondant in half and roll out the first piece into a circle over 9-inches (23 cm) across. Use the same fluted tart tin to cut a piece of fondant the same size as the cookie. Brush the top of the fondant with water and lift it and place it on the bottom-side of a cookie. Brush the exposed side of the fondant with water and carefully adhere the second cookie on it, so that you now have a giant sandwich cookie. Repeat with the second piece of fondant and lastly rolling the remaining scraps to cut and assemble 2 smaller cookies (these will be used for the cookies-&-cream ice cream.
Prepare a 9-inch (23 cm) springform tin by lining the bottom and sides with plastic wrap, so that the plastic comes up and over the sides of the pan.
For the ice cream, whisk the cream, milk, sugar and salt until the sugar has fully dissolved. Pour this into an ice cream maker following manufacturer’s instructions. When the ice cream is almost done mixing, break up the 2 smaller cookies into it and let it mix in so that some pieces of cookie are still visible but some crumbs have worked in. Spoon the soft ice cream into the prepared pan and spread to level it. Cover the ice cream with the overhanging plastic wrap and freeze for at least 3 hours to set.
To assemble the cake, remove the ice cream from the springform pan and unwrap. Place the ice cream on one of the large cookie sandwiches and place the second cookie on top. If you are not serving the cake immediately, wrap the whole cake and place it back in the freezer.
To serve the cake, pull it from the freezer about 20 minutes before serving. Remove it from the pan, peel away the plastic and place on a platter to serve.