01 - Whisk together gluten-free flour, almond flour, sugar, yeast, and salt in a large bowl until thoroughly combined.
02 - Mix warm milk, warm water, egg, and softened butter in a separate bowl. Pour wet mixture into dry ingredients and stir until sticky dough forms.
03 - Shape 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 too soft.
05 - Roll chilled dough on lightly floured surface into 12 x 8-inch rectangle. Place butter layer over bottom two-thirds of dough. 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 all folds, wrap dough and refrigerate for 1 hour before shaping.
08 - Roll dough into 16 x 10-inch rectangle. Cut into 8 triangles using sharp knife or pizza cutter. Roll each triangle tightly from wide end to point.
09 - Place shaped croissants point-side down on parchment-lined baking tray. Cover and let rise in warm place for 1 to 1.5 hours until slightly puffy.
10 - Preheat oven to 400°F. Whisk egg with milk for egg wash. Brush croissants lightly with mixture.
11 - Bake for 20-22 minutes until deep golden brown. Cool slightly on pan before serving.