In a large bowl, beat the caster sugar and butter until pale and creamy. Add the eggs, one at a time, beating after each addition. Add the sour cream, vanilla and continue to beat for a further minute, until incorporated.
Prepare the barbecue for indirect cooking over medium-low heat (170°C to 190°C). If using a Weber Q barbecue, set up your barbecue with a convection tray and a trivet.
Add 1 tablespoon of the flour to a small bowl and add the drained sour cherries. Toss the bowl to coat the cherries with the flour, this will help to stop the cherries discolouring the batter. Add the remaining self-raising flour to the batter and beat over a low speed until fully incorporated. Using a spatula or spoon, fold the floured sour cherries through the batter. Lightly grease the baking tin with cooking oil spray and pour the batter into the tin.
Bake the cake over indirect medium-low heat for 40 to 45 minutes, or until a skewer inserted into the centre of the cake comes out clean.
Whilst the cake is cooking, make the chocolate ganache. Place the white chocolate and thickened cream into a clean glass or ceramic bowl. Microwave on 50% power for 1 to 2 minutes, or until just melted, stirring occasionally. Set aside at room temperature until required.
Once the cake has cooked, remove the cake from the barbecue, leave to cool slightly for 5 minutes before turning out onto a cake cooling rack.
Once the cake and the ganache has completely cooled, drizzle the white chocolate ganache over the cake and finish with a sprinkle of the pistachios.
If you don’t have a Bundt tin, simply use a 20cm round cake tin or Weber Large Casserole Dish.