Question: The base of Jaffa Cakes is an Italian sponge cake named after what city?

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Jaffa Cakes: Jaffa Cakes are biscuit-sized cakes introduced by McVitie and Price in the UK in 1927 and named after Jaffa oranges.  The most common form of Jaffa Cakes are circular, 2+1/8 in in diameter and have three layers: a Genoise sponge base, a layer of orange flavoured jam and a coating of chocolate.  Jaffa Cakes are also available as bars or in small packs, and in larger and smaller sizes.  The original Jaffa Cakes come in packs of 12, 24 or 36.

Layer cake: A layer cake (US English) or sandwich cake (UK English), also called a sandwich in UK English, is a cake consisting of multiple stacked sheets of cake, held together by frosting or another type of filling, such as jam or other preserves.  Most cake recipes can be made into layer cakes; butter cakes and sponge cakes are common choices.  Frequently, the cake is covered with icing, but sometimes, the sides are left undecorated, so that the filling and the number of layers are visible.

Ice cream cake: An ice cream cake is ice cream in the shape of cake with layers of sponge cake in between.  A popular form is a three-layer cake, with a layer of ice cream between two layers of cake.

Frog cake: The frog cake is a dessert in the shape of a frog's head, composed of sponge cake and cream covered with fondant.  It was created by the Balfours bakery in 1922, and soon became a popular treat in South Australia.  Originally frog cakes were available exclusively in green, but later brown and pink were added to the range.  Since then other variations have been developed, including seasonal varieties (such as snowmen and Easter "chicks").  The frog cake has been called "uniquely South Australian", and has been employed in promoting the state.  In recognition of its cultural significance, in 2001 the frog cake was listed as a South Australian Heritage Icon by the National Trust of South Australia.

Misérable cake: A Miserable cake is a type of almond sponge cake that is a traditional Belgian recipe.  The cake is filled with buttercream made by whisking hot sugar syrup into an egg yolk foam, known as a pâte à bombe.  The cake base is made form almonds, known as a joconde.  In Belgium it is served after dinner is a type of petit four.

Angel food cake: Angel food cake, or angel cake, is a type of sponge cake made with egg whites, flour, and sugar.  A whipping agent, such as cream of tartar is commonly added.  It differs from other cakes because it uses no butter.  Its structure comes from whipped egg whites known as a protein foam.  Angel food cake originated in the United States and first became popular in the late 19th century.  It gained its unique reputation along with its name due to its light and fluffy texture, said to resemble the "food of the angels".

Genoise: A genoise ( , , , or ; ] ; "Genoese cake" or "Genovese cake"; rarely spelled "génoise" in English) is an Italian sponge cake named after the city of Genoa and associated with Italian and French cuisine.  Instead of using chemical leavening, air is suspended in the batter during mixing to provide volume.

Bizcocho: Bizcocho (] or ] ) is the name given in the Spanish-speaking world to a wide range of pastries, cakes or cookies.  The exact product to which the word "bizcocho" is applied varies widely depending on the region and country.  For instance, in Spain "bizcocho" is exclusively used to refer to sponge cake.  In turn, in Uruguay, most buttery flaky pastry including croissants are termed "bizcocho", whilst sponge cake is called "bizcochuelo".  In turn, in Chile, Dominican Republic or Bolivia "bizcocho" refers to a sweet dough ("masa") baked with local ingredients, not dissimilar from the "bizcocho" from Spain.  In Ecuador the dough of a "bizcocho" can either be sweet or salty.  The US state New Mexico is unusual in using the diminutive form of the name, "bizcochito", as the name for a locally developed and very popular cookie.

Lamington: A lamington is an Australian cake, made from squares of sponge cake coated in an outer layer of chocolate (or sometimes raspberry) sauce and rolled in desiccated coconut.  The thin mixture is absorbed into the outside of the sponge cake and left to set, giving the cake a distinctive texture.  A common variation has a layer of cream or strawberry jam between two lamington halves.

Balconi: Balconi Dolciaria is a large Italian company specialized in the production of cakes made with sponge cake.  Founded in 1953 as a simple artisanal pastry shop, created by pastry chef Michele Balconi, Balconi has a factory which covers an area of 20,000 square meters, employs 120 people and over 5,000,000 products are produced daily.

Supporting paragraphs: Jaffa Cakes Genoise
Answer: Genoa