Line a baking sheet with a non-stick mat or parchment paper. Print out guides if desired and slip them under your baking surface.

Sift together the powdered sugar and almond flour, discarding the chunks left in the sifter. Stir the sugar almond flour mixture with a whisk a few times to fully incorporate the two. Set aside.

Beat egg whites for about 15-30 seconds with a handheld or stand mixer, or until frothy. With the machine still running on medium, slowing begin adding the granulated sugar. Once all sugar is added, beat on high until soft peaks form when mixer is lifted out.

Add vanilla or other flavoring extract and food coloring paste if desired. (Liquid food coloring is not recommended.) Continue to beat until thoroughly combined and meringue leaves stiff peaks when mixer is lifted out.

Add half the almond sugar mixture and gently fold in with a spatula. When mixed, add the other half and mix it in until the batter is very loose and looks like a “ribbon” as it drips from the spatula into the bowl. Load the batter into a piping bag with a round tip and pipe onto baking sheet following the guides. 

Set the oven to 300 degrees F. Slightly lift the baking sheet and let it fall onto the counter. Bang it in this fashion several times to remove excess large bubbles from the cookies. Let the cookies sit at room temperature for at least 30 minutes, or  until a skin forms over the cookie batter and when touched with a finger does not stick.

While cookies sit out, create the filling by placing the white chocolate in a microwave safe bowl. Pour the cream over the chocolate and place the bowl in the microwave for 30 seconds. Stir and cook for another 30 seconds and repeat until the chocolate mixture is melted and smooth. Set aside to cool.

Place the cookies in the preheated oven and bake for 15-18 minutes, or until set. Remove from the oven, and let cool by sliding them off the hot baking sheet onto the counter. 

When cooled, flip half the cookies over and pipe filling onto the bottom. Place another cookie on top and repeat to create sandwich cookies. Refrigerate for 1-2 days before serving.