First step is to make our starter (biga): mix together with a whisk some flour with some water and the yeast until it turns into a batter like mixture. Let the biga prove until it doubles the size (at 25°C for 30 to 60 minutes).
After the biga has proved we can add the remaining flour, water and salt and work the dough until it comes off the sides of the bowl.
Add the vegan softened butter one bit at a time and keep mixing the dough until once again it comes off the sides (5-10 minutes on high speed). Please note: if you’re mixing the dough by hands you might want to incorporate the water and melted butter to the flour one bit at a time and work the dough for at least 15 minutes.
Once the dough is ready shape it into a ball and allow to prove for another couple of hours or until it doubles the size. In the meantime we can prepare our cook our veggies or chop the vegan cold cuts and cheeses for the filling.
Spread a bit of flour on the working surface and place the risen dough on it.
With the hands flatten the dough into a rough rectangle, then fold both ends to the centre.
Roll the dough into a 1 cm thick rectangle with a rolling pin.
Arrange the cooked vegetables or vegan cold cuts and cheeses on the dough sheet and grate some vegan parmesan cheese and black pepper on top.
Roll the dough lengthwise to form a big sausage, then transfer on a (preferably round) baking tray in the shape of a doughnut. Allow to proof for 2 hours.
Preheat the oven at 180°C (static) and bake the vegan Casatiello for around 45-60 minutes. If you have a thermometer the inside should be at 100°C (212° F) when ready.
Allow to cool for at least 15 minutes before cutting into slices and enjoy the Casatiello.