Line two trays with baking paper and preheat your oven to 210 degrees.
Cut the parmesan cheese into cubes no bigger than 3cm and place in your Thermomix bowl to mix for 10 seconds on speed 9 to grate.
Add the ricotta, feta cheese (broken into 2 cm pieces), baby spinach leaves, 1 egg, onion powder, nutmeg and salt and pepper to your Thermomix bowl and mix for 15 seconds on speed 4 or until all of the ingredients have combined.
Break the extra egg into a small bowl and lightly whisk.
Place the partially thawed pastry squares on your bench and cut in half lengthways. Brush one edge of the pastry with a little of the egg before using a spoon to add an approximately 3cm wide line of mixture down the centre of the pasty.
Roll the pastry (starting from the edge without the egg) to enclose the filling.
Slice the rolls into four equal parts and brush with a little more of the beaten egg and sprinkle with sesame seeds if desired. Repeat process until all the pastry and cheese mixture has been used.
Place these Thermomix Spinach and Three Cheese Rolls into the oven to cook for 25 minutes or until the pastry is golden and crispy.