01 - Whisk together gluten-free flour, almond flour, sugar, yeast, and salt in a large bowl until thoroughly combined.
02 - Combine warm milk, warm water, egg, and softened butter in a separate bowl. Pour the wet mixture into the dry ingredients and mix until a sticky dough forms.
03 - Shape the dough into a rectangle, wrap tightly in plastic wrap, and refrigerate for 45 minutes to firm up.
04 - Slice cold butter into thin slabs. Place between parchment paper sheets and pound or roll into an even 6 x 8-inch rectangle. Chill if butter becomes too soft.
05 - Roll chilled dough on a lightly floured surface into a 12 x 8-inch rectangle. Place butter layer over bottom two-thirds of dough, leaving a border. Fold top third down over butter, then fold bottom third up like a letter.
06 - Rotate dough 90 degrees, roll to 12 x 8-inch rectangle, and fold again. Repeat rolling and folding 2 more times, chilling for 20 minutes between each turn.
07 - After completing the fourth fold, wrap dough and refrigerate for 1 hour to relax the gluten-free structure.
08 - Roll dough into a 16 x 10-inch rectangle. Cut into 8 equal triangles using a sharp knife or pizza cutter. Roll each triangle tightly from the wide end to form classic crescent shapes.
09 - Place shaped croissants on a parchment-lined baking tray, point side down. Cover and let rise in a warm place for 1 to 1 1/2 hours until slightly puffy.
10 - Preheat oven to 400°F. Whisk egg with milk for egg wash. Brush croissants lightly with the mixture, avoiding excess pooling.
11 - Bake for 20 to 22 minutes until deep golden brown and flaky. Let cool slightly on the baking tray before serving warm.