Preheat oven to 350 and butter sides of an 8-inch round cake pan. Line the base with greased parchment paper. Set aside.
Mix together flour, brown sugar, cinnamon, allspice, and coriander, then rub the butter into the mixture until it resembles coarse bread crumbs. Spoon half of this mixture over the base of the prepared pan.
Whisk the egg and nutmeg into the milk, then add to the remaining flour mixture to make a very runny batter. Stir thoroughly. Pour the batter over the crumbs in the pan.
Bake for 70 minutes, or until golden brown and springy to touch in the center. Cool in the tin for a few minutes, then turn out and cool thoroughly on a wire rack.
*Note: If you can't find self-rising flour, substitute an equal amount of all-purpose flour and add 1 tbsp baking powder and 1 tsp salt.