01 - Preheat the oven to 400°F. Line a baking tray with parchment paper and set aside.
02 - Heat olive oil in a skillet over medium heat. Sauté the minced garlic for about 30 seconds until fragrant, then add the chopped spinach. Cook for 2 to 3 minutes, stirring occasionally, until the spinach is fully wilted. Remove from heat and let the mixture cool slightly.
03 - In a mixing bowl, combine the cooled spinach with crumbled feta cheese, softened cream cheese, black pepper, and nutmeg. Stir until all ingredients are evenly blended and the mixture is uniform.
04 - Roll out the gluten-free puff pastry on a lightly floured surface using gluten-free flour. Spread the spinach and feta filling evenly across the pastry, leaving about a ½-inch border along one long edge to help seal the roll.
05 - Starting from the long side covered with filling, gently but firmly roll the pastry into a tight log. Brush the bare edge with a small amount of beaten egg and press gently to seal the seam.
06 - Using a sharp knife, slice the log into 16 even pieces, each about ¾ inch thick. Arrange the pinwheels cut side up on the prepared baking tray, leaving a little space between each for expansion.
07 - Brush the tops of each pinwheel generously with the remaining beaten egg to ensure a deep golden finish during baking.
08 - Bake in the preheated oven for 20 to 25 minutes, or until the pinwheels are puffed and golden brown. Allow them to cool for a few minutes on the tray before serving warm or at room temperature.