Preheat the oven to 150°C (300°F). Line a baking sheet with a silicone mat.

In a mixing bowl, sift together almond flour and powdered sugar.

In a separate bowl, whip the egg whites until foamy, then gradually add granulated sugar and continue to whip until stiff peaks form.

Gently fold the dry ingredients into the egg whites until the mixture flows like lava.

Add food coloring if desired, and mix until fully incorporated.

Transfer the batter to a piping bag and pipe small circles onto the prepared baking sheet.

Let the macarons sit at room temperature for 30 minutes to form a skin.

Bake in the preheated oven for 15 minutes, then let cool completely.

In a mixing bowl, beat the softened butter until creamy.

Gradually add powdered sugar and beat until well combined.

Add kiwi puree and vanilla extract, mixing until smooth and fluffy.

Pair up the macaron shells by size.

Pipe a dollop of kiwi buttercream onto the flat side of one shell and sandwich with another shell.

Repeat with remaining shells and filling.