Wearing food grade disposable gloves, work green food coloring gel into white rolled fondant or gum paste until desired color is achieved.
Roll the fondant into a thin even layer with a small fondant rolling pin on a cutting mat lightly dusted with powdered sugar to prevent sticking.
Use a sharp paring knife to cut out small leaf shapes, measuring about ½ to ¾-inch in length. Lightly press the knife into the top of the leaves to make vein patterns.
Allow the leaves to dry at room temperature while you make the macarons.
Make the Macaron Shells:
Place the macaron mats or parchment paper on top of upside down half baking sheets. Slide the apple templates underneath the mats.
Place a large round tip, like a #12, in a disposable piping bag. Fold over the top of the bag and place it in a tall glass or in a piping bag holder so it will be easy to fill with the batter. Set this aside.
Sift together the oat flour and the powdered sugar in a medium-sized bowl, then whisk to combine them completely. Set this bowl aside.
126 grams oat flour, 126 grams powdered sugar
Place the egg whites in the bowl of a stand mixer fitted with the whisk attachment and beat on medium-high until frothy. Add the cream of tartar, then slowly add the granulated sugar, one spoonful at a time, with the mixer still running.
Add the vanilla extract and the red food coloring gel until a deep, bright red color is achieved. Continue to beat the mixture until the meringue forms stiff peaks. Remove the bowl from the mixer.
1 teaspoon vanilla extract
Using a rubber spatula, carefully fold ⅓ of the flour/powdered sugar mixture into the meringue. Then add the remaining ⅔ of the flour mixture and continue folding until the ingredients are fully incorporated and the batter falls off the spatula in clumps, just before you reach the figure 8 stage. See note about macaronage.
Once the batter is the proper consistency, transfer it to the prepared piping bag.
Pipe the batter into apple shapes on the first tray using a V-shaped motion. See note. Once the batter has been piped on a full tray, slam the tray down hard on the counter or a table several times to force any air bubbles to the surface. If desired, take a toothpick and pop large bubbles then smooth out the hole left after the bubble pops.
Remove the macaron templates from underneath the mat of the first tray and slide them under the mat of the second tray. Repeat the piping and slamming process and then do the same with the remaining 2 trays. Make sure to remove the templates from the final tray!
Allow the batter to dry at room temperature for 40 minutes. Meanwhile, preheat the oven to 300°F.
Bake the shells, one sheet at a time, for about 12-14 minutes, rotating the pan half way through.
Allow the shells to cool completely on the mats before removing them. To remove more easily, push up on the mat from underneath to help them pop off. If you have trouble with them sticking, that may mean they are underbaked. Some of the shells in the center of the tray may have a little bit of sticking. Very carefully use a stiff metal spatula to pry them off the mat, taking care not to rip the shell.
The cooled shells can be stored in a single layer in an airtight container in the refrigerator or freezer, or you can fill them immediately. If you must stack them to store, separate them with layers of parchment paper so they don't stick together.
Make the Filling:
Sprinkle the apples with lemon juice.
½ tablespoon lemon juice, 4 small apples
Combine dry ingredients in large bowl.
½ cup dark brown sugar, 1 teaspoon cinnamon, ⅛ teaspoon nutmeg, ¼ teaspoon sea salt
Add the apples to the dry ingredients and toss to mix. Add the vanilla and cream and mix thoroughly. Set aside.
½ teaspoon vanilla, 2 tablespoons heavy cream
Melt the butter in a skillet.
2 tablespoons butter
Add the apple mixture and cook approximately 8-10 minutes, until the apples are soft and the liquid has turned golden.
Combine the cornstarch and water in a small bowl. Add to the apple mixture, stir and continue to cook for a few minutes until thickened.
1 teaspoon cornstarch, 4 teaspoons water
Cool the filling, either at room temperature or in the refrigerator, and use immediately or store in the fridge for up to a week.
Make the Buttercream:
Dissolve the apple cider drink mix in the boiling water. Allow to cool.
1 packet instant apple cider mix, 1 tablespoon boiling water
In a stand mixer fitted with the whisk attachment, beat butter, cinnamon and salt at medium-high speed until smooth, about 20 seconds. NOTE: If using a hand-held mixer, increase mixing times by at least 50%.
10 tablespoons butter, ½ - 1 teaspoon cinnamon, ⅛ teaspoon salt
Add the powdered sugar and beat at medium-low speed until most of the sugar is moistened, about 45 seconds.
4 ounces powdered sugar
Scrape down bowl and beat at medium speed until mixture is fully combined, about 15 seconds; scrape bowl, add the heavy cream, and beat at medium speed until incorporated, about 10 seconds.
½ tablespoon heavy cream
Increase speed to medium-high and beat until light and fluffy, about 4 minutes, scraping down bowl once or twice. This step is important to create a smooth and whipped buttercream.
Assemble the Macarons:
Add the buttercream to a disposable piping bag fitted with a medium-sized round tip, such as #12.
Pair up the macaron shells by size so the top and bottom of each sandwich will match.
Pipe a dam of buttercream around the edge of the flat side of each bottom shell. Spoon a small amount of apple filling inside the buttercream dam. You will have buttercream and filling leftover.
Place a single pretzel stick into the buttercream at the top of the macaron to represent the apple stem. Place a fondant leaf into the buttercream next to the pretzel stick.
Place the top shells on top and press down slightly by holding onto the outer edges of the shells. Take care not to crush the shells.
Refrigerate the assembled macarons until ready to serve. For best texture and flavor, allow the macarons to come to room temperature before enjoying. Macarons can be frozen in an airtight container.
I highly recommend weighing the ingredients listed in grams. French macarons are notoriously finicky and require precise measurements. I recommend using cracked whole eggs, not store bought egg whites.
100 grams of egg whites is the equivalent of the whites from approximately 3⅓ large eggsThe process of folding the dry ingredients into the meringue is called macaronage. For oat flour macarons, you want to undermix the batter compared to traditional almond flour macarons. With traditional macarons, you want the batter to flow like a ribbon off the spatula, but with oat flour macarons the batter will fall in clumps. If you overmix, the batter will be too thin and the shells won't have the proper structure.Use the buttercream immediately or store in refrigerator. If refrigerated, allow frosting to come to room temperature before use. Buttercream can also be frozen. Storage: Store the assembled cookies in an airtight container in the refrigerator for up to several days. If refrigerated, allow the cookies to come to near room temperature before serving. You may freeze the macaron shells or assembled macarons. Thaw before serving. Nutritional information is only an estimate and will vary based on your ingredients and substitutions.