Heat oven to 175C. Prepare three 7" cake tins by greasing with butter and lining with circles of greaseproof paper.

In a food processor, blend the cooked butternut squash until smooth. (I simply mashed it in a bowl with a potato masher)

In a mixing bowl, mix together the oat flour and baking powder and set aside.

In a separate bowl, beat together the margarine and sugar until light and fluffy. (I used an electric hand whisk for this step)

Mix together the butternut squash and melted chocolate.

Gradually add half the eggs into the creamed margarine and sugar. Don't panic if it looks split.

Fold in half the oat flour/baking powder mixture.

Fold in the rest of the eggs along with the melted chocolate/butternut mixture.

Finally fold in the rest of the oat flour.

Pour the cake mixture into the three greased and lined 7" cake tins.

Bake for 20-25 minutes then take out of the oven and cool in the tins before turning out onto a wire rack to cool completely. The cakes will be quite crumbly, so keep any crumbs aside in a small bowl and be careful as the cakes will be fragile.

Meanwhile, make the filling. Blend the cornflour with about one third of the milk, while bringing the rest of the milk to the boil in a small milk/nonstick saucepan along with the sugar and cocoa powder, whisking to keep it smooth.

Add the milk and cornflour and stir it constantly with a wooden spoon while it comes to the boil. It will become a smooth thick chocolatey custard. (if it is not smooth, use a stick blender to blitz it smooth, as it needs to be really silky)

Pour the filling/custard into a large bowl, place cling film over the surface (it needs to be touching the entire surface to prevent a skin forming) and put it into the fridge until cooled completely. This will take at least an hour.

On a serving plate, spread the first cake with chocolate custard filling using a palette knife to spread it from the middle outwards and leaving a small gap around the edges to allow for squidging.

Each time you remove the greaseproof paper from the cakes, use a butter knife to scrape off the crumbs and keep them with the rest of your stash of crumbs for later.

Next, carefully place the next cake on top, top and spread with chocolate custard/pudding then repeat with the third cake.

Cover the outside of the cake with the chocolate custard/pudding.

Finally, take your crumbs and sprinkle them over the top and sides of the cake (depending on how many you have leftover). Make sure you do this soon after 'icing' the cake, so the crumbs stick to the wet custard.

Any leftover custard and cake crumbs can be made into an extra little dessert by sprinkling the crumbs on top of the custard... Call it the baker's perk! 👩‍🍳👨‍🍳

Place the cake into the fridge for 2 hours to chill, before bringing it out to come back up to room temperature before serving.