For the macarons: Sift the almond flour with the powdered sugar in a bowl.
In a saucepan on high heat, bring the granulated sugar and 3 tablespoons water for the syrup to 230 degrees F on a candy thermometer, 3 to 5 minutes. When the sugar syrup reaches about 190 degrees F, start whipping 2 egg whites. Whip until they reach full peaks, and then slowly add the boiling syrup. Continue to whip on medium-high speed until they are completely cooled and you have a shiny meringue, about 10 minutes.
Mix the remaining 2 egg whites and the sifted almond/sugar and carefully fold into the meringue. Add the orange zest and food coloring.
Preheat the oven to 320 degrees F. Line baking sheets with silicone baking mats.
Fill a pastry bag fitted with a plain tip with the meringue and pipe macarons about 3 inches in diameter on the prepared baking sheets. Tap the baking sheets to get rid of any air bubbles, and let dry out at room temperature for about 10 minutes. (Optional: Blow some disco dust or edible glitter on top of the macaroons before tapping, to give them a shimmer.)
Bake for 12 to 18 minutes, depending on your oven. Check to see if the macarons are done by grabbing the top of one macaroon and trying to shake it. They are done when the top barely slides against the skirt. If they are not done, extend the baking time by 2 minute intervals, checking after each extension. Allow to cool fully before trying to take them off the baking sheet.
For the ganache: Gently melt the chocolate in a microwave-safe bowl and transfer to a food processor. Bring the corn syrup and cream to a boil, and then stream into the chocolate with the machine running. Slowly stream in the olive oil. Transfer to a bowl and let the ganache set up in a cool place for about 2 hours.
When the ganache is firm, transfer to a piping bag with a small 1/4-inch round tip and pipe about 1/4-inch ganache on one side of the macarons. Sprinkle with a few grains of salt and sandwich with the other macarons.
Recipe courtesy of Zac Young