Cook the pasta normally according to the instructions on the packet until al dente.
In the meantime, peel and chop onions and garlic cloves. Briefly sweat the onions and garlic in a larger pan. Remove the rind from the Gorgonzola, then add it to the pan and melt it in it over a low heat. Then add the spinach and simmer everything over medium heat for about 15 minutes. Season to taste with salt and pepper. Serve with the pasta.
Also tastes great with a large dash of whipped cream.