In a large mixing bowl, combine the yeast, sugar and warmed milk. Stir until the yeast is dissolved and let it sit for 5-10 minutes or until it becomes frothy.

Add in 2 cups of the flour and begin to mix on low using the dough hook attachment of your stand mixer. Add another cup of flour, the dairy-free butter, egg and vegemite and mix on medium/low speed until the dough starts to form. Add in the remainder of the flour and the parmesan and mix until the dough starts to pull away from the sides of the bowl. The dough will still be quite sticky.

Turn the dough out onto a well floured surface and knead with floured hands for 5-10 minutes or until it becomes smooth and elastic. Gently shape the dough into a ball.

Place the dough ball back into the bowl that has been greased with oil and cover it with a tea towel. Leave it to rise in a warm, draught-free place for 1 hour or until it has doubled in size.

Punch down the dough to release the air and turn the dough out onto a floured surface and shape the dough into a ball.

Line a 9 x 13 inch (20cm x 30cm) tray with baking paper and set aside. Cut the dough ball into 4 even pieces, and then cut each piece into 3 so that you have 12 pieces in total. Roll each piece into a ball and place evenly into the pan. Cover again with the kitchen towel and set aside in a warm place for 20 minutes.

Before the second rise is complete, preheat the oven to 180°C. Mix together the additional flour, water and vegemite to make a thick paste. Brush the tops of the buns with the beaten egg yolk. Place the paste into a piping bag or zip lock bag and snip off the end. Once the buns have finished rising, pipe crosses onto each and sprinkle over a little extra grated parmesan cheese. Place the buns in the oven for 30 minutes, or until browned on top and they make a hollow sound when you tap the top.

Let the buns cool on a wire rack before serving warm with dairy-free butter.