Green’s Dictionary of Slang

a round tart made of sugar, apple and bread, sold in the streets.

1859, 1860		Hotten Dict. of Modern Sl. etc.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 198/2: Among the regular articles of this street-sale are [...] ‘Bowlas,’ or round tarts made of sugar, apple, and bread.
1873		Sl. Dict.