Step 1: Prepare the spinach. If using fresh spinach, sauté it briefly in a pan until wilted. If using frozen, thaw it completely and squeeze out all excess water very thoroughly using a clean kitchen towel or paper towels. This step is crucial to prevent a watery filling.
Step 2: Make the filling. In a medium-sized bowl, combine the prepared spinach, crumbled feta cheese, ricotta or cream cheese, minced garlic, finely chopped onion, dried oregano, and a pinch of nutmeg. Season with salt and pepper to taste, then mix all ingredients together until well combined.
Step 3: Prepare the phyllo. Carefully unroll the phyllo pastry sheets. Place them on a clean, dry surface. Keep any unused sheets covered with a lightly damp (but not wet) kitchen towel to prevent them from drying out and cracking while you work.
Step 4: Assemble the roses. Take one sheet of phyllo pastry and brush it lightly but evenly with olive oil or melted butter. Fold the phyllo sheet lengthwise in half. Brush the folded sheet again lightly with oil or butter. Place about 1-2 tablespoons of the spinach-feta filling in a line along one short end of the folded phyllo strip.
Step 5: Shape the roses. Carefully roll the phyllo strip tightly once over the filling to enclose it. Then, begin to coil the strip around itself to form a "rose" or spiral shape. Place the formed phyllo rose into a muffin tin (for individual portions) or arrange them snugly on a baking sheet lined with parchment paper. Repeat with the remaining phyllo sheets and filling.
Step 6: Bake. Preheat your oven to 375°F (190°C). Brush the tops of all the assembled phyllo roses with any remaining olive oil or melted butter. If desired, sprinkle with optional grated parmesan cheese and sesame seeds or crushed nuts for extra flavor and texture. Bake for 20-25 minutes, or until the phyllo is golden brown and delightfully crispy.
Step 7: Serve warm. Allow the phyllo roses to cool for a few minutes before serving. They are best enjoyed warm, straight from the oven.