Mix all the batter ingredients together until well incorporated. Set aside.
Core donut peaches with an apple corer or a fruit knife and peel off the skin with a peeler.
Prepare crumble coating by rubbing flour with butter cubes with finger tips until mixture resemble breadcrumbs. Mix in sugar and crushed biscuits. Chill in the refrigerator until required.
Set your oven to 180C and prepare baking tray lined with parchment paper.
Dip one peach at a time into batter making sure it is well coated. Drip away excess before dropping into crumble mixture. Pack the crumble mixture around peach and place on baking tray. Repeat this process until all peaches are completed.
Bake in pre-heated oven for 20-25 mins or 12-15 mins in batches if using an air fryer.
Cool baked peaches on cooling rack and chill for 30 mins before decorate with toppings.