Tuesday, October 23, 2012

The Greatest Cupcake Ever Made! / honey-roasting nuts




Take a good look dawgs, below is the greatest cupcake ever made! No joke, there is zero room for improving this baby*.  


The construction:

Devil’s food cake – when it comes to chocolate cake bases for cupcakes, nothing beats a devil's food cake.  Moist, rich, and medium-density.  A great complement to either richer or lighter frostings.

Butterscotch frosting – I’ve been wanting to learn how to make butterscotch for a while, the flavor is similar to some of my favorite things, like chai tea, thai tea…the list goes on-ish.

White chocolate cherry mousse – Adding an element of sweetness and tartness to counter the rich frosting and cake.  Whoever makes a cupcake without a filling is terribly misguided.  Filling fixes the common cupcake quandary of the cake/frosting ratio, such that there’s variety in every bite.  (Note: I’ve recently seen another clever solution offered here: http://www.buzzfeed.com/peggy/22-things-youre-doing-wrong #3).

Spicy honey roasted peanuts – Just like the benefits of adding a filling, “toppings” or garnishes can add more contrast and flavor elements to the cupcake.  One thing I never understand is when a cupcake is topped with the same flavoring used in the frosting. Why?? Blueberries on blueberry frosting, popcorn on popcorn frosting, or crumbs from the cake sprinkled on top all may add texture, but the flavor is redundant.  I decided to use nuts primarily for a) varied texture, b) complementary flavor to the other components, and c) seamless introduction of heat, adding a whole new dimension to the cupcake experience.  Just one of several possible ingredients for these purposes was peanuts.

Now each of these components could probably get its own article, but this week I wanted to investigate what it was about roasting nuts in honey that produced that crunchy, sweet-and-savory business.  Typically when I’ve been in the mood for honey roasted nuts, I’d just toss some nuts (usually walnuts) in a small amount of honey, sprinkle with salt, spread them out on foil, and bake for about 15 minutes at 400oF.  Other recipes I’ve seen online ask for lower temps, bake for roughly the same amount of time, and suggest varied techniques and ingredient proportions.  The results could range anywhere from nuts that were grossly burnt or were sticky rather than crunchy.  Clearly, the problem here is eliminating variability in order to get consistently solid honey-roasted nuts every time.

So what exactly is going on in the honey roasting process?  It turns out honey roasting works just like many other candy-making procedures.  Honey initially contains about 18% water by mass, with the rest being a mixture of sugars.  As the water evaporates in the oven, the sugar molecules can come closer together and form a crystal structure. 

Left: sugar solution with high relative water content (blue/red balls = water molecule, orange hexagons = sugar molecule). Right: sugar solution post-heating, water has evaporated allowing sugar molecules to begin to  bond with each other, or crystallize.
Given that honey basically only has two components (water, miscellaneous sugars), and that an oven is a well-controlled environment for heat exchange, I thought this would be an easy enough process to model. BUT the tricky thing about roasting honey is that as water evaporates, the chemical composition changes.  As the chemical composition changes, the boiling point changes.  Also, as the temperature of the honey rises, the heat flow from the honey diminishes.

A  MATLAB model was fitted to observed sugar stages of honey roasted at 400 degrees in order to estimate oven heat transfer coefficient.  This model was then used to predict behavior of honey roasting at 350 degrees.  If you want to look at the code or want more details on how I made the model, feel free to ask in the comments.  It is by no means a perfect model, btw.
Long story short, I put together a program that modeled the steady loss of water from roasted honey.  I first collected “data points” by roasting tablespoons of honey in the oven at 400o F for 3, 9, 12, and 15 minutes before checking which candy stages the honey “syrup” was at.  I fit my model to this data to find the heat transfer coefficient of my oven.  I then used this parameter to model honey roasting nuts at 350o F at 7, 10, 16 and 19 minutes (I observed that 400o F tends to over-roast the nuts).

7 minutes - the honey behaved like..warm honey (“thread stage”, still ~18% water).

10 minutes – the honey formed a firm ball when dropped into water (“firm ball stage”, 13% water)

16 minutes – the honey was beginning to darken, and when dipped in water could be pulled to form thin flexible threads (“soft crack stage”, 5% water)

19 minutes – the honey is still dark, but when dipped into water and stretched formed brittle pieces (“hard crack stage”, 1% water)

Left: honey at the “firm ball” stage.  Center: honey at the “soft crack” stage – a thin flexible thread can be pulled.  Right: honey at the “hard crack” stage – the honey can be pulled to form thin threads/points that break when bent.
With this model, I was able to derive some key lessons when honey roasting nuts:

  1. Using more honey doesn’t increase cooking time, so long as the exposed surface area scales by about the same factor.  Meaning, the recipe I give below can be scaled however you want.
  2. Decreasing the honey:nut ratio only matters to the extent when virtually all the honey is coating nuts – this results in a significant increase in surface area and decreased cook times.  The honey also acts as a buffer to the heat of the oven, keeping nuts from burning. Stick to the ratio I recommend, or err on the side of extra honey.
  3. Related to number 2, distribution of the nuts matters.  By spreading nuts out, you also increase the chance of the thin layer of honey flowing off the nut.  By keeping the nuts all together, there is better honey coverage for all.



A “loose” recipe:

Devil’s food cake

A solid recipe from the food network kitchens, http://www.foodnetwork.com/recipes/food-network-kitchens/devils-food-cake-recipe/index.html if you’re a die-hard from-scratch kind of person.  Otherwise, just work from a box.

Butterscotch frosting

A thorough recipe found here http://www.food.com/recipe/butterscotch-frosting-87307.  Following the technique closely is VERY important here.
 
White chocolate cherry mousse
  • 12 oz white chocolate
  • 1 can cherries (sweet or tart)
  • 1 cup heavy cream
  • 2 tbsp butter
  1. Heat white chocolate in the microwave using 10 second intervals, stirring in between, until fully melted
  2. While melted chocolate is still hot, stir in butter cut into 1tbsp pieces.
  3. Heat a ~1/4 cup of cherry juice from the can in a saucepan until you see bubbles stacking on top of bubbles.  The juice is now a syrup!
  4. Using a food processor, stand mixer, hand mixers, a whisk, or a fork (not recommended), whip the heavy cream until stiff peaks are visible.
  5. Stir one third of the whipped cream into melted chocolate to lighten.
  6. Stir in one tablespoon of the cherry syrup.
  7. Fold in the remainder of the whipped cream into the melted chocolate (be gentle, you don’t want to force air out of the mousse)
  8. Lightly fold in 1-2 tbsp of cherry syrup to create pink streaks in your mousse
  9. Refrigerate until use in cupcake filling

Spicy Honey Roasted Peanuts
  • 1/3 cup peanuts
  • 2 tbsp honey
  • 1 tsp salt (more to taste)
  • 3 tsp chili powder§
  1. Toss peanuts, and honey in a bowl until peanuts are well coated.
  2. Line a baking tray with foil, and then on top with a sheet of parchment paper (optional, but makes it possible to remove nuts when cooled).
  3. Dispense peanuts and honey into the center of the parchment paper (spread out so you have no nuts stacking on top of each other, but do not spread nuts apart from each other).
  4. Bake at 350o F for 20 minutes, stirring once halfway through with a wooden spoon to re-coat all nuts.
  5. Upon removing nuts, quickly stir the nuts one more time to re-coat
  6. Sprinkle salt, chili powder, and other flavorings while the nuts are still hot and sticky

*ok maybe the shape could be improved and the frosting job could be neater or fancier, but that’s just aesthetics
If you’re one of those people who only like to work from fresh ingredients, have fun pitting, juicing and straining about a half cup of cherries.
other types of nuts can be used, I like walnuts since their crevices tend to trap more honey
§ any kind of chili powder can be used.  If you want nuts with a lot of heat, consider mixing in some chili-infused oil with the honey instead.

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