To make the salted caramel: Place 1/3 cup granulated sugar (80 g) in a saucepan and heat over medium heat to make a dry caramel. Meanwhile, in another saucepan, heat the heavy cream.

Once the sugar has turned into an amber caramel, remove the pan from the heat and add a small amount of the hot cream. Be careful, as it may splatter. Stir quickly and gradually add the rest of the cream. When the bubbling stops, add the salted butter and mix again until you have a medium-thick cream. If the caramel seems too thin, return the pan to low heat and stir until you reach the desired consistency. Chill in the refrigerator.

To make the macaron shells: A few days ahead, separate the egg whites from the yolks.

Pulse the powdered sugar and toasted almond flour together in a food processor, then sift the mixture.

In a small saucepan, heat the water and 1/3 cup granulated sugar (80 g) to make a sugar syrup. Cook until it reaches 212°F (100°C), checking with a candy thermometer. When the syrup reaches 212°F, place half of the egg whites in the bowl of your stand mixer and start whisking on low speed. Gradually increase the speed so the whites become foamy for the next step.

When the syrup reaches 244°F (118°C), reduce the mixer speed to medium and slowly pour the syrup in a thin stream over the foamy egg whites. Try to pour it directly onto the mixture, not onto the whisk or sides of the bowl, so the syrup goes into the meringue. Add food coloring if desired.

Continue whisking, increasing the speed again, until the mixture cools down to about 95–105°F (35–40°C). The meringue should be smooth, glossy, and form stiff peaks. This is important to ensure the meringue is firm enough; otherwise, the batter may be too runny. Add the remaining half of the unbeaten egg whites to the bowl and mix just to combine, not to whip them.

Switch to the paddle attachment, add the almond flour and powdered sugar mixture all at once, and mix on low speed for 1 minute to start folding the batter.

Continue folding the batter by hand with a spatula until it is smooth and flows like a thick cake batter. You should achieve the classic 'ribbon' stage. To fold, use a motion that goes from the bottom of the bowl up the middle and then up the sides, pressing the batter against the bowl while turning it (avoid lifting too much to prevent incorporating air).

Fill a piping bag fitted with a plain round tip with the slightly warm batter. Remove any air bubbles from the bag by pressing with the back of a knife, for example. Pipe the batter in staggered rows onto your baking sheet. If you’re not using a template, be sure to space the macarons apart, as they will spread slightly.

Tap the baking sheet firmly on the counter a few times to release any air bubbles, smooth the tops, and remove any peaks from piping.

Let the macaron shells sit in a dry place for 30 minutes to 1 hour, until they are no longer sticky to the touch.

Preheat your oven to 300°F (150°C). When the resting time is up, bake the macarons for about 13 minutes. After about 7 minutes, open the oven door slightly for 2 seconds to let out steam. Open again for 2 seconds after 10 minutes. This helps prevent cracking.

Once the shells have cooled, fill them with the salted caramel. Take the macarons out of the refrigerator about 15 minutes before serving.