Preheat the oven to 190° C.
Whisk the eggs together until well combined, season with salt, then add half Parmesan cheese. Mix well all together.
Butter a rectangular baking tin (30 x 40 cm) and then place on top of a buttered foil of baking paper.
Pour the eggs mixture into the baking tin and put in the oven for 10 minutes.
Melt the remaining butter in a pan together over a medium heat and fry the garlic until golden.
Reduce the heat and add the spinach, season with salt and a twist of nutmeg.
Cook for about 5 minutes, then stir into the remaining Parmesan cheese and mix well everything together.
Remove the Frittata from the oven, spoon over a layer of spinach, ham and Provola cheese, leaving a border.
Roll it up carefully, using the edge of the baking paper.
Cut into not too fine slices and serve.