Iced Coffee Cake — an espresso layer cake with coffee buttercream

i. Origin & history

'Coffee cake' means two quite different things depending on which side of the Atlantic you are on, and the confusion is worth settling first. In North America, a coffee cake is traditionally a single-layer cake, often with a cinnamon streusel crumb topping or a swirl of fruit, eaten at breakfast or with mid-morning coffee; it usually contains no coffee at all. It descends from the yeasted Kaffeekuchen and streusel cakes brought by German, Dutch and Scandinavian immigrants, and became a quick baking-powder cake in the twentieth century.

In Britain and much of the Commonwealth, a coffee cake is a sponge flavoured with coffee and covered in coffee icing — most famously coffee and walnut cake, a teatime and village-fête classic since at least the mid-twentieth century, when bottled coffee essence such as Camp coffee and then instant coffee made it easy to flavour a sponge. 'Iced coffee cake' in this sense simply means a coffee cake with icing.

The cake on this page sits between the two: a coffee-flavoured American-style butter cake with coffee buttercream, the kind of layer cake found in North American bakeries and coffee shops, especially as espresso culture spread through the United States from the 1980s and 1990s. It shares its method with the British coffee sponge, but borrows the American habit of brushing layers with syrup and finishing them with a generous, swirled buttercream.

Coffee as a dessert flavour is much older, of course. Coffee creams, ices and soufflés were fashionable in eighteenth- and nineteenth-century France and Italy; Italy has affogato and tiramisu; and Austria-Hungary built a whole café culture around cake. For other coffee desserts on DessertCat, see the coffee soufflé and the espresso panna cotta.

ii. How to make a cake taste strongly of coffee

The usual disappointment with coffee cake is that it tastes of sugar and butter with only a faint hint of coffee. The problem is concentration. Brewed coffee, even espresso, is more than 98 per cent water; to get a strong flavour you would need so much of it that the batter becomes thin and the cake heavy, and buttercream would split. The solution is instant espresso powder (or good instant coffee) dissolved in the smallest possible amount of boiling water — a paste many times stronger than brewed coffee, which flavours intensely without adding much liquid.

That coffee is then used in three layers. Some goes into the batter, where baking mellows it into a warm, roasted background. More goes into a coffee syrup brushed onto the warm sponges, which soaks in and gives a moist crumb with a sharper, fresher coffee note. The rest goes into the buttercream, where the fat carries the aroma and gives the first and strongest hit of flavour. Together they read as coffee rather than 'coffee-ish'.

Brown sugar helps, too. Its molasses has caramel and roasted notes that sit well with coffee and underline its bitterness, where white sugar simply makes it sweeter. A pinch of salt in the buttercream does the same job, cutting the sweetness of the icing sugar so the coffee comes forward.

Finally, the coffee must be cool when it meets butter. A hot coffee paste beaten into buttercream melts the butter and splits the icing into a greasy, curdled mess; the paste should be at room temperature, and added gradually.

iii. Ingredients

Makes 12 servings · scroll the side panel to adjust

• 4 tbsp instant espresso powder, divided
• 225 g unsalted butter, softened, for the cake
• 225 g light brown sugar
• 4 large eggs, at room temperature
• 225 g plain flour
• 2½ tsp baking powder
• ¼ tsp fine salt
• 2 tbsp whole milk
• 50 g caster sugar, for the syrup
• 250 g unsalted butter, softened, for the buttercream
• 450 g icing sugar, sifted
• 1 tsp vanilla extract
• ⅛ tsp fine salt, for the buttercream
• 12 chocolate-covered coffee beans or walnut halves, to decorate

Instant espresso powder gives the strongest, cleanest flavour; good-quality instant coffee granules work, dissolved in the same amount of water. The 4 tbsp are divided: 2 tbsp for the cake, 1 tbsp for the syrup and 1 tbsp for the buttercream, each dissolved in boiling water as described in the method. Light brown sugar adds caramel depth; caster sugar gives a paler, lighter cake. For the classic British version, fold 75 g chopped walnuts into the batter and decorate with walnut halves. Decaffeinated instant espresso works just as well if you are serving it in the evening.

iv. Method

1. Heat the oven to 175 °C (350 °F), or 160 °C fan. Grease two 20 cm round cake tins and line the bases. Dissolve 2 tbsp of the espresso powder in 2 tbsp boiling water and leave to cool.
2. Beat the 225 g butter and the brown sugar for 4–5 minutes until pale and fluffy. Beat in the eggs one at a time, adding a spoonful of the flour with the last one if the mixture looks curdled.
3. Sift in the flour, baking powder and salt and fold in gently. Fold in the cooled coffee paste and the milk until just combined.
4. Divide between the tins, level and bake for 22–25 minutes, until risen, springy and a skewer comes out clean.
5. While the cakes bake, make the syrup: stir 1 tbsp espresso powder and the caster sugar into 60 ml boiling water until dissolved. As soon as the cakes come out, prick them all over with a skewer and brush the syrup evenly over both. Cool in the tins for 10 minutes, then turn out onto a rack and cool completely.
6. For the buttercream, dissolve the last 1 tbsp espresso powder in 1 tbsp boiling water and cool. Beat the 250 g butter for 2 minutes until very soft, then beat in the icing sugar gradually, followed by the coffee paste, vanilla and salt. Beat for 3 minutes more until light and fluffy, adding a splash of milk if it is too stiff.
7. Place one sponge on a plate, spread with a third of the buttercream, top with the second sponge and cover the top and sides with the rest. Decorate with coffee beans or walnut halves around the edge.

v. Tips & common mistakes

• Use instant espresso, not brewed coffee. A concentrated paste gives strong flavour without thinning the batter or splitting the buttercream.
• Cool the coffee paste. Hot coffee melts butter. Add it to the batter and icing only once it is at room temperature.
• Syrup the cakes while hot. Warm sponge absorbs syrup evenly; cold sponge leaves it pooling on the surface.
• Season the buttercream. A pinch of salt cuts the sweetness of the icing sugar and makes the coffee taste stronger.
• Beat the butter well first. Very soft, creamy butter gives a smooth, light buttercream; cold butter gives lumps.
• Taste and adjust. Instant coffees vary widely in strength; taste the buttercream and add a little more paste if needed.

vi. Variations

Coffee and walnut cake, the British classic, folds chopped walnuts into the batter and tops the cake with walnut halves. Mocha cake adds 2 tbsp cocoa to the batter and 50 g melted dark chocolate to the buttercream. A tiramisu-style cake replaces the buttercream with sweetened mascarpone whipped with cream and dusts the top with cocoa. Iced coffee loaf bakes the batter in a loaf tin for 45–50 minutes and tops it with a simple coffee glaze. The batter also makes about 18 coffee cupcakes.

For more coffee desserts, see the light coffee soufflé and silky espresso panna cotta. Austria's Kardinalschnitten layers meringue and sponge with coffee cream, and France's dacquoise is often filled with coffee buttercream.

vii. Serving & storage

Serve at room temperature, in generous slices, with a cup of coffee or tea in the afternoon or as a dessert with a glass of dessert wine or a coffee liqueur. A spoonful of crème fraîche on the side balances the sweetness.

The cake keeps in an airtight container at cool room temperature for up to 3 days, as the buttercream seals in moisture; in warm weather refrigerate it for up to 5 days and bring it back to room temperature for an hour before serving, as cold buttercream is hard and dull in flavour. The unfilled sponges freeze, well wrapped, for up to 2 months; the buttercream can be frozen separately and re-whipped after thawing. It is a good make-ahead cake — the flavour deepens overnight.

ix. More from North American

• Coffee Soufflé — airy hot coffee dessert
• Espresso Panna Cotta — silky coffee cream
• Marble Cake — swirled chocolate and vanilla
• Golden Sponge — American yellow layer cake
• Kardinalschnitten — Viennese coffee-cream slices
• Blackout Cake — Brooklyn chocolate layer cake