Rhubarb Financier
From the blog For Love of the Table
150 g. (10 T. plus 2 t.) unsalted butter
60 g. (1/2 cup) slivered blanched almonds
60 g. (1/2 cup) all-purpose flour
1/4 t. salt
120 g. (a generous 1 cup) powdered sugar
4 egg whites (120 grams)—beaten until foamy
125 g. (trimmed weight) rhubarb, sliced cross-wise in 1/2-inch pieces (a generous 1 cup sliced rhubarb)
25 g. (2 T.) sugar
Spread the almonds on a baking sheet and toast in a 350° oven until light golden brown—about 5 minutes. Cool and using a nut grinder, grind the nuts to a flour. (You may use 60 grams of purchased almond flour instead. If using almond flour, spread it on a baking sheet and toast as you would the slivered almonds.)
Meanwhile, place the butter in a small saucepan set over medium heat. As the butter begins to sputter and pop, whisk occasionally. The butter solids will begin to turn brown. When the solids are a golden brown and the butter has a pleasantly nutty aroma, scrape the butter (making sure to get all the browned bits) to another container to stop the cooking process (you should have 120 g. browned butter).
Place the ground almonds, all-purpose flour, salt & sugar in a medium sized bowl. Whisk to combine. Whisk in the egg whites. Whisking constantly, drizzle in the warm browned butter to incorporate. Continue to whisk until the batter is smooth. Refrigerate the batter overnight. (This will allow any developed gluten to relax and will give the butter time to firm up.)
To prepare the rhubarb: In a small bowl, toss the rhubarb together with the sugar. Cover and refrigerate overnight. The next morning, give the rhubarb a quick fold to help dissolve any remaining sugar hanging out at the bottom of the bowl. Strain the rhubarb liquid into a sauté pan large enough to hold the rhubarb in a single layer. Bring the liquid to a boil over high heat; add the rhubarb to the pan and return to the boil. Remove the pan from the heat and let the mixture cool to room temperature. Strain the cooled rhubarb out and place in a small bowl. Return the liquid to the pan and set the pan over high heat. Reduce the liquid to a syrup. Scrape the syrup (there shouldn't be more than a tablespoon) over the rhubarb and toss to combine. Chill until ready to use. (See notes.)
To bake the financier: Butter and flour a rectangular (roughly 4 1/2- x 13 1/2-inches) removable bottom tart tin. (If you don't have a rectangular tin, an 8-inch round tart pan—or even a shallow cake pan—will work too.) Spread the batter in the pan and arrange the rhubarb chunks on top of the batter (leaving any excess syrup behind in the bowl)—it is not necessary (or desirable) to press the fruit into the batter.
Transfer the pan to a 375° oven and bake until the cake is golden brown, puffed in the center and a toothpick inserted in the cake (not the fruit) comes out clean—about 25 minutes. If there was any syrup remaining from the rhubarb, brush this over the warm cake. When the cake is cool enough to handle (but still warm) remove the outer rim of the pan. Set the cake on a wire rack and cool completely.
To serve the financier, dredge with powdered sugar and slice cross-wise into 6 portions.
Notes:
Because financiers use such a large quantity of egg whites, a good time to make them is after you have made something that uses a lot of yolks (ice cream, pot de crème, cream pie, etc.).
For the rhubarb, you can use the exact same method that I did for the rhubarb streusel coffee cake if you prefer. The method described here may seem a bit more convoluted...but I think it works better for the smaller amount of rhubarb required for this recipe. When executed properly, both methods produce the same thing.
http://www.forloveofthetable.com/2013/05/a-rhubarb-financier.html