Coffee and Caramel Macarons

Instructions

1. In a large bowl, combine the icing sugar, ground almonds and coffee.
2. In another bowl, whisk the egg whites with an electric mixer until soft peaks form. Gradually add the sugar while whisking until stiff peaks form and the meringue is shiny.
3. Add the meringue to the dry ingredients. Using a spatula, mix until shiny and sticky. The mixture should be smooth and should drop slowly from the spatula.
4. With the rack in the middle position, preheat the oven to 325°F (165°C). Line two baking sheets with parchment paper. Using the inside of a 1 ½-inch (4 cm) round cookie cutter as a guide, trace 24 circles evenly spaced out on each sheet of parchment paper. Flip the parchment paper over and place on the baking sheets.
5. Transfer the meringue mixture into a pastry bag fitted with a ½-inch (1 cm) plain tip. On each baking sheet, pipe 24 macarons on the inside of the traced circles. Tap the baking sheets on a work surface two or three times to slightly flatten out the macarons. Let sit for 20 minutes to let the tops of the cookies dry out slightly. This step gives the macarons their distinctive smooth tops and protruding rims.
6. Bake one sheet at a time for 20 minutes. Let cool completely, about 1 hour. Gently peel the macarons off the baking sheets.
7. Meanwhile, in a bowl, whisk the dulce de leche, butter and fleur de sel with an electric mixer until the mixture is pale and creamy. Cover and refrigerate for 30 minutes. Whisk again until stiff peaks form.
8. Transfer the dulce de leche mixture into a pastry bag fitted with a plain tip. Cover the flat bottoms of half of the macarons with the dulce de leche. Close with another cookie to form a sandwich. Place in an airtight container and refrigerate for at least 8 hours to soften the macarons, or you can freeze the cookies at this point, if desired. Let sit out at room temperature for 30 minutes before serving.