Cinnamon Basil Crumb Cake (Steamed)

[ Equipment: steamer or steam oven. For more information about the terminology in this recipe, see Low Temperature Baking: A Journey of 3 Paths ].

The title of this recipe is not a typo: it's really a steamed crumb cake. Crumb cakes are usually baked in dry heat, because the topping is supposed to be dry and crumbly. On this cake, the topping is crumbly but moist, similar to those on the individually wrapped coffee cakes sold in delis and convenience stores. In a regular crumb cake recipe, a high-temperature oven hardens the streusel into a fragile crust. Here, the oven is powered by steam, so the topping starts off dry, almost white and powdery. As it cooks, it absorbs water from the steam and aggregates into a blanket of delicious, soft brown pebbles.

Besides the unusual topping, this recipe illustrates a technique common in the assemblage of steamed cakes. Because steaming is so efficient, a cake can built up in a series of flash-steamed layers. This recipe demonstrates the versatility of that technique. The plumped raisins float just above the bottom of the cake, although the batter itself is not sufficiently buoyant to support the raisins. The trick is a thin strip of batter poured into the pan and flash-steamed as a platform for the raisins. Similarly, the crumb topping would sink if sprinkled over the cake batter. Instead, it goes on after the body of the cake has finished steaming.

The inspiration for the flavoring is an herb called cinnamon basil. It's not available at my local markets, so I simulated the ingredient by mixing regular basil and powdered cinnamon. An accurate substitution would be a pinch of cinnamon per teaspoon of dried basil. For a crumb cake, I thought the cinnamon should be more assertive, so the flavoring is half cinnamon and half basil. The taste of basil remains distinct. Even the raisins are re-hydrated in basil-infused water.

The cake itself is a cottony-soft sponge cake, leavened with egg foam and a tiny amount of baking powder. The high ratio of cornstarch to flour is the reason for the fluffy texture. The applesauce and higher sugar content give the cake its moistness - it has double the sugar-to-egg ratio of a basic Genoise cake. The weight of that extra sugar partially collapses the egg foam, hence the need for the baking powder boost.

The instructions for beating the egg foam repeatedly state that the batter should be heated until all the sugar has been mixed in and dissolved. The recipe was formulated with an electric whisk as the mixing device. Electric whisks are not as fast or powerful as a high-speed stand mixer or even a handheld two-beater electric mixer, and the heating expedites the formation of the egg foam. If the recipe is implemented with a high-speed mixer, it may be possible to omit the heating, although I have not tried it that way.

Here are a few more tips for assisting the egg foam to maximum height:

• Fresh baking powder - the recipe specifies only a little baking powder, so it must be fresh. Test the strength of baking powder by putting a tiny spoonful in hot or boiling water and seeing how much it fizzes.
• Beat the egg foam a lot - even when the egg foam forms a ribbon when dripped from the beaters, it's doesn't hurt to continue beating it for a few minutes more, because the egg foam stabilizes with longer beating time.
• Greased and floured pan - out of laziness, I don't always flour my pans. With egg foam batters, however, it's a good idea to do that always. Pans with only grease are slippery, and the batter can't grip the sides and pull itself up.
• Rolling boil - a rolling boil means that the inside of the steamer is thick with steam and thicker steam means more heat transfer to the pan, which invigorates the air bubbles and the baking powder reaction in the batter.
• Don't wait - if the batter begins "bubbling", steam the cake at once. Bubbling is a sign that the batter is losing air. Low temperature cakes need all the leavening power they can get to puff up.

A final thought: if the crumb topping steams up too dry, try making it with a very little more butter. It's easy to add too much butter, and then the topping could turn out soggy.

Makes 1 cake, 8 servings

- 83 calories per serving
- Oven Temperature: Steamed

Basil Infused Raisins:

• 1/8 cup raisins
• 1 tablespoon coarsely chopped, fresh basil (or 1 teaspoon dried basil)
• 1/2 cup boiling water

Crumb Topping:

• 1 tablespoon brown sugar
• 1 tablespoon rolled or instant oats
• 1/8 cup all-purpose flour
• 1/2 tablespoon butter
• 1/8 teaspoon ground cinnamon

Sponge Cake:

• 3 tablespoons all-purpose flour (1 oz)
• 1 tablespoon cornstarch (0.3 oz)
• 1 teaspoon non-fat milk powder
• 1/4 teaspoon dried basil
• 1/4 teaspoon ground cinnamon
• 1/4 teaspoon baking powder
• pinch of salt
• 1 tablespoon applesauce
• 1 tablespoon milk (regular or low-fat)
• 1 large egg
• 1/4 teaspoon vanilla extract
• 1/4 cup sugar

Basil Infused Raisins Method



1. Put basil and raisins in a heatproof cup. If using dried basil, crush it in a mortar or between fingers to release flavor. Pour in hot water and infuse for at least 30 minutes.



2. Strain and reserve raisins, discarding water and basil.

Crumb Topping Method:



1. If oat flakes are larger than 1/4 inch, pulse them in a coffee grinder or food processor for 2 or 3 seconds to chop them up a little. Put dry ingredients in a small bowl and mix until well combined. Add butter, cut into small chunks.



2. With fork, cut butter into flour mixture until topping is uniformly crumbly. Set aside.

Cake Method:



1. Cut a strip of aluminum foil 6 inches wide and at least 11 inches long. Press the foil into a small loaf pan (5-3/4 x 3 x 2 inches) to cover the bottom and the long sides. Grease and lightly flour the pan. Set aside.



2. Mix the applesauce and milk in a small dish and set aside.



3. Bring sauce pot with at least 1 inch of water to a simmer. In a large metal bowl, lightly whisk the egg, 1/8 cup of sugar and vanilla extract until frothy. Take sauce pot off heat and place bowl over sauce pot. The hot water must NOT touch the bowl. While monitoring the temperature of the egg mixture with an instant-read thermometer, gently stir the mixture until it reaches 100F/38C. Remove bowl from sauce pot.



4. With an electric whisk or mixer, whip the egg mixture on high speed until it is pale yellow and double in volume and forms a thin ribbon that lasts 2 to 3 seconds when dripped from the beater. This step should take about 3 to 5 minutes.



5. Bring the sauce pot back up to a simmer and remove from heat. Put the bowl over the sauce pot. Beat until the mixture forms a thicker ribbon that lasts at least 15 seconds when dripped from the beater. The temperature of the batter should never exceed 110°F/43°C or the heat will cook the egg foam. If the batter gets too hot, remove it from the sauce pot and continue beating as it cools. When the batter attains the thicker ribbon stage, remove the bowl from sauce pot.

The first picture above shows the thicker ribbon that remains visible for a count of 15 before completely dissolving. The second picture above shows that the batter should now be so light and thick that a small amount will mound in the beater.



6. Sprinkle in a portion of remaining sugar. Put bowl back over hot water and beat on HIGH until dissolved. At this stage, the batter should not exceed 100°F/38°C. Repeat until all remaining sugar has been mixed into the batter and remove from the sauce pot. The sugar will partially collapse the egg foam and the ribbon will only stay on the surface for about 5 seconds. Continue beating another 4 or 5 minutes on HIGH to stabilize the batter and cool.



7. Alternately, FOLD in portions of the applesauce and flour mixtures. The applesauce should be dripped along the edge of the batter. The flour should be sifted over the batter. Repeat until all the applesauce and all of the flour have been incorporated.



8. Bring steamer water to a rolling boil. Pour 1/4 cup of the batter into the loaf pan and tilt the pan to fully coat the bottom of the pan with batter. Steam the batter for 3 minutes. Remove.



9. Sprinkle basil raisins over the steamed cake base.



10. Pour the remaining batter into the cake pan over the raisins and even out. Grease the underside of a sheet of aluminum foil large enough to fit over the pan. Cover the pan with the foil and crimp the foil against the pan ledge to secure it. Put the pan in the steamer and steam for 30 minutes. Check the steamer's water level periodically; the water should be at a rolling boil.



11. Remove from steamer. Carefully remove the foil without tearing it. Sprinkle crumb topping over the cake. Re-cover the pan with the foil, crimping it loosely in place and allowing enough room so the topping does not press against the foil. Return to steamer and steam for another 15 minutes. At this stage, the water does not have to be at a rolling boil - a medium boil will suffice.



12. Remove from steamer and remove foil. Cool in pan for 15 minutes. Loosen cake from short sides with a knife and lift the cake out of the pan by grabbing and pulling up on the aluminum foil flaps. Peel off foil and cool cake on a rack for 30 minutes.



13. Slice and serve.