Step 1In a large, heavy-bottom saucepan, briefly cook the frozen spinach in a little boiling water, stirring just until thawed. Remove from heat and drain the spinach well, discarding the water. Return the spinach to the pan.
Step 2Stir in the mozzarella and Romano cheeses, along with the one-quarter cup butter to form the filling. Season to one-eighth teaspoon salt and a small pinch each pepper and cinnamon, or to taste. Mix the filling well; the warmth from the pan and spinach will melt the other ingredients slightly. This makes 3 cups filling.
Step 3Working quickly, brush 2 sheets phyllo with a light coating of melted butter, and place 1 sheet on top of the other. Place one-third cup filling along the length of the sheets, leaving 2 inches at either end. Turn in the ends and roll the filling into the sheets, as with a burrito; continue folding until a long roll is formed. Brush the roll lightly with melted butter and place on a baking sheet. Continue until all of the filling is used, spacing the rolls about 2 inches apart. This makes 6 rolls.
Step 4Bake the rolls until golden brown, about 20 to 25 minutes, rotating halfway for even coloring. Cool slightly, then cut each roll diagonally into 2-inch pieces. Serve warm.