For the crust, combine all the dry ingredients together then drizzle in butter stirring until everything is fully moistened. Press into the base and up the sides of a 8 or 9” springform pan, or a pie plate. Set aside.
Let the ice cream soften slightly, then measure into a large bowl. Stir in the custard powder, mixing until soft and smooth. Spread over crust, cover ice cream surface with plastic wrap and freeze for 2-3 hours or until firm.
Melt chocolate and cream together, stirring until smooth. Let sit for about 5 minutes to cool, then quickly remove plastic wrap and pour over ice cream surface. Tilt pan to spread chocolate evenly, then freeze until set or ready to eat.
Notes
-If you can't find Bird's, any gluten free custard powder will do. -For dairy free, replace the heavy cream with 2 Tbsp dairy free margarine or shortening