Preheat the oven to 180C/350F and spray an 8x8 inch square pan with cooking spray.
Make the fruit filling first. Peel, core and slice your apples into 2-3mm slices. Try and keep your slices as even as possible, so the apples cook at the same time. Place into a medium sized bowl.
Add the blackberries, light brown sugar, cornflour, cinnamon and vanilla into the bowl with the apples and stir until all of the fruit is coated in flour and sugar. Leave to one side.
Next, make the biscoff cobbler topping: Place the flour, sugar, baking powder and salt into a medium sized bowl. Place the biscoff in a small, heat proof bowl and microwave for 30 seconds. It should look like a Biscoff puddle!
Place your butter/vegan butter into another small, heat proof bowl and microwave in 20 second increments, until melted.
Add the melted biscoff and butter into your flour mixture and stir until well combined. You'll have some larger bits of dough and some smaller. It should look like very coarse breadcrumbs with a few large lumps.
Add in the milk, 1/2 tbsp at a time (I needed the full 1tbsp) and mix until one large lump of dough forms. It will look like biscuit dough at this point, that's fine.
Tip the fruit mixture into your prepared pan, making sure to get as much of the sauce as possible. Spread into an even layer.
Taking a dessert spoon, spoon lumps of the cobbler dough onto the fruit. You don't want to cover the fruit completely, I sort of squished a bit of dough into the side of the bowl with my spoon, then dropped that onto the fruit, so the topping wasn't too thick.
Alternatively, you can use a cookie scoop. However, I find that this makes the cobbler topping too thick, so you get this great big ball of dough and not enough fruit ratio. It looks and tastes better with the cobbler topping about 1/2-3/4 inch thick.
Place the cobbler into the oven at 180C/350F for 35-40 minutes. Remove from the oven and use a fork to try and get a bit of apple from the centre. Test to see if the fork goes straight through the apple. If there's no resistance, they're cooked. Take a skewer and pierce the centre of the cobbler too. It should come out clean. If it's not done, it will come out with a few wet looking crumbs on.
If the cobbler still looks a little wet inside and the apples aren't tender, turn the oven down to 160C/325F and bake for a further 10-15 minutes. Be aware that because the dough is quite brown anyway, it doesn't really go golden like a traditional dough does, so, it's harder to see when this cobbler topping is done! My cobbler took 35 mins at 180C/350F and 15 minutes at 160C/325F.
Once the cobbler is baked, remove from the oven and leave to cool for at least 30 minutes before serving. I love to serve this warm from the oven with vanilla ice cream. You can also serve with custard or cream.
Apple Blackberry Biscoff Cobbler will keep covered, in the fridge, for 3 days. Bring up to room temperature to serve. However, I think it's best served warm. You can reheat servings in the microwave for 30-45 seconds.