Place a sauce pot of salted water over high heat. Once boiling, add the spaghetti and cook until al dente.
In a pan set over medium heat, melt the butter and crush in the garlic cloves. Once the pasta is just cooked, add garlic to the noodles.
Reduce the heat to low, and add the marmite. Begin tossing the spaghetti and add in a little pasta water to loosen. Toss a couple of times to coat, then grate in the majority of the cheese. Toss again to coat the spaghetti.
Plate the spaghetti, season with salt and pepper and sprinkle with grated Parmesan.