Sift confectioners' sugar into a medium bowl. Sift in coconut flour.

Beat egg whites in a separate bowl using an electric mixer until white and foamy. Add white sugar slowly. Beat until mixture is glossy and forms stiff peaks.

Sift the coconut flour mixture into the egg whites, a few tablespoons at a time, folding after each addition. Batter should be thick and gooey and able to fall off a spoon slowly like lava.

Fit a piping bag with a coupler and a tip. Drop piping bag tip-down into a tall glass and fold edges down around the glass. Spoon batter into the bag. Gather edges and twist together.

Holding the tip at a 90 degree angle, pipe batter onto a greased baking sheet to form individual macaron shells. Tap baking sheet onto a countertop to remove air bubbles. Let sit until dry, 15 to 60 minutes.

Preheat the oven to 300 degrees F (150 degrees C).

Bake in the preheated oven until tops are firm, 15 to 20 minutes.

Puree raspberries in a food processor, adding water if using frozen raspberries. Strain out the seeds using a fine-mesh strainer.

Beat butter and 1/2 the confectioners' sugar in a bowl using an electric mixer until combined. Add the remaining 1/2 and beat until creamy. Add raspberry puree and heavy cream; mix well to make the frosting.

Spoon a small amount of frosting over the flat side of a macaron shell; cap with another shell. Repeat with the remaining filling and shells.