Preheat oven to 400°F. 

Line 2 baking sheets with parchment paper and set aside. 

Make your barm by placing 1/2 c. of flour in a medium sized bowl. Add your water and ale, whisking until fully combined. Whisk in the sugar and yeast. Cover the bowl with plastic wrap and allow to rest for 15 minutes. 

In a large bowl, whisk together 4 c. flour, sugar, and spices for the dough. 

Once the barm is ready, whisk the egg and the milk together in a small bowl. Add the egg mix to the large bowl with the spiced flour and add 1/2 c. barm. Work together with your fingers until you get a soft dough. If the dough does not come together, add another 1/4 c. of barm. 

Place dough on a lightly floured surface and shape into an 8" x 10" rectangle, about 1/2" thick. Cut the rectangle into 20 pieces, about 2" square. 

Roll each square into a ball and place on the baking sheets, making sure they are evenly spaced. 

Use a knife to cut a large, deep "X" into the top of each ball but be sure not to cut all the way through to the bottom. 

Cover the pans with a kitchen towel and allow to rest for 30 minutes.

Bake for 15-18 minutes, rotating the pans halfway through. 

Transfer buns to a cooling rack to cool. 

Whisk together the powdered sugar and cornstarch in a small bowl. 

Sift the powdered sugar mixture over the top of the buns.