Prepare circle templates. I made 1 1/2-inch circles on a piece of paper 1/2-inch apart. Line baking sheets with parchment paper, placing the template under the parchment.
In a food processor, pulse a third of the Powdered Confectioners Sugar (2.33 ounce) and the Hazelnut Flour (4 ounce) to form a fine powder.
Sift the hazelnut flour mixture twice, and sift the remaining Powdered Confectioners Sugar (4.67 ounce) twice.
In a large bowl, combine the hazelnut flour mixture and the sifted powdered sugar.
In the bowl of a stand mixer, add whites of the Egg (4). Using the whisk attachment, whisk whites on medium speed until foamy.
Gradually add the Granulated Sugar (3.5 ounce). Once all sugar is added, scrape down the sides of the bowl. Increase mixer speed to high and continue whisking until stiff, firm, glossy peaks form.
Sift the hazelnut flour mixture 1/3 at a time over the egg white mixture. Carefully fold using a large silicone spatula until mixture is smooth and shiny. Repeat process for the remainder of the powdered sugar mixture.
Place the macaron mixture into a piping bag with a round tip. With the piping tip 1/2-inch above the template, pipe 1 1/2-inch circles onto parchment paper-lined baking sheets.
Once finished, gently tap baking sheet on your work surface to release any air bubbles and help form the "feet" of the macarons. Let macarons stand at room temperature for 30 minutes.
During this time, preheat oven to 375 degrees F (190 degrees C). Macarons will be ready to bake when they no longer stick to your finger when lightly touched. Do not forget to remove the template paper before baking.
When ready, bake for 10 to 15 minutes or until they are crisp and firm. Rotate baking sheets halfway through to promote consistent baking.
Remove from oven and let cool for 2-3 minutes. Then carefully remove the macarons from parchment paper and place on a wire rack to cool completely.
Make the filling. In a stand mixer, cream together the Butter (1 cup) and Powdered Confectioners Sugar (2 cup), until smooth.
Add the Caramel Topping (1/2 cup) and mix well.
Add the Coffee Extract (1 teaspoon) and mix until fully incorporated. The buttercream should be really firm to pipe it properly, so I popped mine in the fridge for 15 minutes before using it.
Place filling in a piping bag with round tip. Pipe filling onto one macaron and then sandwich it together with another one. Repeat for remaining macarons.
Macarons should be placed in the fridge for 24 hours before eating. This is how they mature and reach their full flavor. You can eat one right away, but when you eat one the next day it will be so much better. Be patient and enjoy!