From S., 27 February 2010, A specific recipe request.
Q: Will the panna cotta recipe be on your blog? Now that I must contemplate a gluten-free life, I am making lots of panna cotta. Had a great coconut panna cotta at Cafe Atlantico in January. And just bought some matcha powder in (of all places) North Carolina.
A: Thanks for asking for the recipe. Panna cotta is one of the easiest desserts to prepare, comprising only cream, milk, and sugar, barely set with gelatin. Its name literally means “cooked cream,” even though the cream generally is heated only enough to dissolve the gelatin and sugar. For a dessert so simple, panna cotta has been an ample source of drama in recent years: described in lurid terms on both Top Chef, where it was prepared incorrectly, and Top Chef Masters, where Rick Moonen executed it perfectly. Speaking of Top Chef, panna cotta has tripped up more than one professional under time duress. One added far more gelatin than necessary, producing the dreaded “hockey puck”; another experienced the opposite problem. Still another discovered that fresh pineapple and gelatin don’t mix, and that a dessert combining the two will not set.
Why all the difficulty? It all comes down to the gelatin. In the US, professional kitchens tend to rely on sheet gelatin, and home cooks on powdered gelatin. (In many European countries, however, sheet gelatin is widely available.) Unfortunately, sheet gelatin comes in different strengths based on its setting capacity, or its Bloom strength. If you are strongly mathematically inclined and have a sensitive digital scale, you can convert quantities among Bloom strengths using this formula:
Q(Bloom 2) = Q(Bloom 1) * √(Bloom 1÷Bloom 2)
where Q = mass in grams. Gelatin sheets come in different masses – 160 bloom gelatin tends to come in 2.5g sheets, and 200 bloom gelatin in 2g sheets. The difference in mass makes it possible to interchange these types of sheets. Powdered gelatin is generally 225 bloom.
Want to avoid the hard math? Don’t have a kitchen scale? Remember the following conversion. For every sheet of gelatin in a recipe, divide by 2 to obtain the number of teaspoons of powdered gelatin.
I have found that a ratio of one sheet of gelatin or half a teaspoon of powder per cup of liquid yields perfect panna cotta. Because gelatin melts at 95F/35C, the milk and cream must be heated to at least that temperature to incorporate the gelatin.
Matcha panna cotta
2 c whole milk
2 c heavy cream
1/2 c sugar
4 sheets gelatin OR 2 tsp powdered gelatin
2 tsp matcha
bittersweet chocolate or fresh berries
Combine the milk, cream, and sugar in a pan. Place over medium low heat and bring to 160F/70C to dissolve the sugar. Remove from heat.
Soften the gelatin sheets in a bowl of cold water until they feel soft, like jellyfish. Squeeze out excess liquid and add to the hot milk mixture. If using powdered gelatin, soften in 1 tbsp cold water and add to hot milk. Whisk well to melt gelatin and combine.
Place the matcha in a small bowl and add a small quantity (about 2 tbsp) of the hot mixture. Whisk well to combine. Strain through a chinois or fine sieve into the rest of the mixture. Pour into molds and chill until panna cotta is set.
Garnish with shards or curls of bitter chocolate, or with fresh berries.