Hazelnut Macarons with Sweet Potato Buttercream Filling

Recipe and photo contributed by Johnisha Levi Yield:  40 cookies
Prep Time:  1 hour Cook Time:  1 hour 15 minutes

Hazelnut Macarons with Sweet Potato Buttercream Filling

Johnisha’s fall-inspired recipe makes any holiday a truly extraordinary occasion. While making macaroons does take time, it’s worth every second. The delicious shell recipe is adapted from Kathryn Gordon's "Les Petits Macarons: Colorful French Confections to Make at Home".

Ingredients

Shells:

1¼ cups (165 grams) packed hazelnut meal

¾ cup (65 grams) packed confectioners’ sugar

¾ cup (150 grams) granulated sugar

¼ cup water

4 large egg whites (115 grams)

¼ teaspoon cream of tartar

Filling:

1 can (15 ounces) sweet potato puree, organic Farmer’s Market brand preferred

1¼ cup maple syrup

3 large egg whites (100 grams), room temperature

Pinch of cream of tartar

¼ teaspoon salt

3 sticks (340 grams) unsalted butter, cut into cubes, room temperature

Instructions

To make the hazelnut macaron shells: 

  1. Line four baking sheets with silicone mats or parchment paper. Prepare a piping bag with an 806 round tip. Set aside a pastry brush with a small container of water.
  2. In a food processor, pulse the hazelnut meal with the confectioner’s sugar to eliminate any large clumps. Set aside in a medium bowl.
  3. Combine the granulated sugar and water in a small saucepan, taking care to keep the sides of the pan as clean as possible. Over medium heat, stir to dissolve the sugar, continuing to keep the sides as clean as possible. Meanwhile, in a stand mixer fitted with a whisk attachment, whip the egg whites and cream of tartar on medium speed until the egg whites form soft peaks. Turn down the egg whites to the lowest speed when they reach soft peaks so as not to over-whip.
  4. When the sugar begins to simmer, stop stirring and use a digital or candy thermometer to monitor the temperature. If any sugar crystalizes on the side of the saucepan, dip the pastry brush in water, and lightly brush the side until it disappears.
  5. Once the sugar syrup reaches 235°F, remove the saucepan from the heat. With the mixer on the lowest speed, carefully pour the syrup in a steady stream into the egg whites without touching the whisk attachment or the side of the bowl. Increase the mixer speed to medium and whip until the egg whites are stiff and shiny (resembling marshmallow fluff) and the meringue does not shift in the bowl when it is turned upside down, 4 to 5 minutes. It is okay to proceed if the meringue is still slightly warm but not hot.
  6. Scrape the meringue into a large bowl with shallow sides. Sprinkle half of the hazelnut meal over the surface of the meringue, folding the meal until it is almost incorporated. Sprinkle the remainder of the hazelnut meal over the meringue. Continue to fold until the meal is thoroughly incorporated, and the batter drops slowly from the edge of the spoon in a more or less continuous ribbon, before slowly disappearing into the surface of the mix after a few seconds. The batter should not be runny or watery, but still viscous. (Alternatively, the batter is also ready for piping when, after tilting the bowl, the batter slowly shifts toward the other side.)
  7. Working quickly, fill the piping bag and pipe 1-inch discs onto the prepared baking sheets. Firmly rap each baking sheet 4 to 6 times against the counter to eliminate any air bubbles.
  8. Let the baking sheets stand at room temperature until the surface of the piped shells are matte and no longer tacky. This should take between 30 minutes but can take up to 1 hour depending upon the humidity in the kitchen and outside. Preheat the oven to 300°F convection mode (or 325°F for a conventional oven).
  9. Bake the shells one sheet at a time on the middle rack until the macaron “feet” are fully formed, 6 to 8 minutes. Rotate the tray and reduce the temperature to 275°F convection (or 300°F for a conventional oven), and bake until shells, when gently pulled, are not wiggly or are only slightly wiggly and do not quite fully detach from the silicone or parchment., 3 to 5 minutes.  If you notice the shells beginning to brown before the macarons are ready to come out of the oven, crack the oven door open for the remaining minutes. (See Kitchen Tips about testing a few first to see how your oven works so you can decide how to cook these best in your oven).
  10. Carefully slide the parchment or silicone mat onto a baking rack to cool completely. Use an offset spatula to carefully remove shells. Fill and store following procedure below.

To make the sweet potato buttercream filling:

  1. In a small saucepan, cook the sweet potato puree over medium-low heat, stirring frequently, until thickened and liquid has evaporated, 10 to 15 minutes. Set aside in a heatproof container to reach room temperature.
  2. In a medium saucepan, bring the maple syrup to a boil, stirring frequently to keep it from bubbling above the edge of the saucepan. Use a digital or candy thermometer to monitor the temperature. Meanwhile, in a stand mixer fitted with a whisk attachment, whip the egg whites and cream of tartar on medium speed until they form soft peaks. When the egg whites reach soft peaks, reduce the mixer to the lowest speed so as not to over-whip.
  3. Once the maple syrup reaches 238°F, remove saucepan from the heat. With the mixer on the lowest speed, carefully pour the maple syrup into the egg whites so that it does not hit either the whisk attachment or the side of the bowl. Increase the speed to medium and mix until the meringue is stiff, shiny, and room temperature to the touch, approximately 15 minutes. (If it is still warm, it will melt the butter).
  4. Add the salt, and then the butter to the mixture gradually, continuing to whip until the buttercream is no longer curdled and appears satiny. Add half the sweet potato puree to the mixture, and mix on medium speed until incorporated. Add the second half of the puree, continuing to mix on medium speed until incorporated.
  5. Fill a piping bag with an 806 tip or use a small offset  spatula to spread or pipe a neat circle of buttercream, about 1 teaspoon, onto a macaron shell and gently press a second shell on top until the buttercream comes just to the edge of the shell.
  6. Cover and refrigerate the filled macarons for 1 day to allow flavors to develop. Filled macarons may be stored in an airtight container in the freezer for up to 1 month. Let stand at room temperature for 10 minutes before serving.

Kitchen Tips

From the Test Kitchen:

  • Make this kosher for Passover by replacing the confectioners’ sugar with homemade powdered sugar. We recommend this recipe from Martha Stewart.

Ingredients Notes:

  • The hazelnut meal may be substituted with an equal amount of pecan meal, walnut meal, or almond meal.  Bob’s Red Mill brand works very well.
  • 225 grams of baked sweet potato that has been processed through a food mill may be substituted for the canned sweet potatoes.
  • For super smooth hazelnut shells, after you process the hazelnut meal and confectioner’s sugar, sift through a fine mesh strainer.
  • Although not highly recommended, if you want to make a dairy-free version, simply use  a non-dairy, non-hydrogenated margarine, spoon for spoon, in the buttercream. You can switch out 2 teaspoons of the margarine for solid coconut oil and add it along with the margarine. The buttercreams will each taste different, and the coconut oil will be a bit softer, but  they are still completely delicious.

Preparation and Baking Notes:

  • The hallmark of a macaron is the so-called “foot” (pied), a frilly edge that forms at the bottom of the shell upon baking. Letting the macarons dry out (crouter), so that they form a thin crust is key. As the shells bake, the crust prevents the batter from escaping through the top; instead, it pushes through the base, creating the decorative foot. Both over and under folding the batter can also impact foot formation.
  • Half the battle of baking macarons is controlling oven temperature. If the macarons bake at too low of a temperature, it will result in a flat shell with less than pronounced feet and/or the shell may remain raw inside. If the macarons bake at too high a temperature, they will brown too much and become crunchy. Every oven is different, so to experiment to find the right temperature setting, pipe four macaron shells on a separate piece of parchment and bake shells as a tester to gage the proper oven temperature before proceeding with the entire batch.  If they come up brown too fast, use a second baking sheet under the primary sheet to insulate the bottom.
  • If you bake the macarons until they completely detach from the silicone, they will likely be too crunchy by the time they cool.
  • Older, room temperature egg whites will yield best results for meringues.

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