1-First Step: Prepare the dry ingredients. Sift 100 g almond flour and 100 g powdered sugar together into a large bowl. Discard any large bits. This creates a fine powder key to smooth shells in your space cookies.

2-Second Step: Make the meringue base. In a clean bowl, whip 40 g egg whites with a pinch of cream of tartar on medium speed until foamy. Gradually add 100 g granulated sugar, one tablespoon at a time. Beat on high until stiff peaks form, about 8-10 minutes. The meringue should be glossy and hold shape.

3-Third Step: Divide and color the batter. Split meringue into three bowls: one plain, one with purple color, one with navy blue, and a tiny bit black in the blue. Fold 35 g remaining egg whites into the dry mix, then incorporate each meringue portion separately for swirled galaxy macarons.

4-Fourth Step: Macaronage technique. Gently fold each colored batter 30-40 times until it flows like lava. Test by drawing a figure-8; it should not break. Avoid overmixing to prevent flat cookies.

5-Fifth Step: Pipe the shells. Fill piping bags with each color. Pipe 1.5-inch circles on parchment-lined sheets using a template underneath. Tap sheets firmly 5 times to release air bubbles. Rest at room temperature for 30-60 minutes until dry to touch.

6-Sixth Step: Bake. Place in preheated 300°F oven for 15-18 minutes. Rotate halfway. Cool completely on sheets before peeling off.

7-Seventh Step: Prepare filling. Beat 100 g butter until creamy. Add 200 g powdered sugar gradually, then vanilla and cream. Divide into three, color purple, blue, black. Pipe swirls on half shells and sandwich.

8-Final Step: Let mature in fridge for 24 hours for best texture. Serve at room temp for stunning swirled space cookies. Troubleshooting table below helps if issues arise.