Mince onion and garlic (more onion than garlic).
In a large pot, pour olive oil to cover the bottom, then add onion and garlic and turn on medium heat to brown.
Add hamburger and brown on all sides (amount of hamburger depends on number of eaters).
Add spaghetti sauce, stir to mix in the hamburger, onion and garlic, add a little water (about 1/2 a jar), then cover and simmer on low heat.
In another, larger, pot, heat water to boil (water should be about 2/3 of the way to the top of the pot).
Once water is boiling, add spaghetti and cook about 10 minutes, stirring and checking the pasta (taste test frequently; pasta should be slightly "chewy" - don't let it get too soft!).
When pasta is done, strain the water and return the pasta to the pot, add a little butter and stir to blend (so the pasta doesn't get "sticky").
Add sauce (pour it right over the spaghetti in the pot, or transfer everything to a big bowl). And serve!