Cut the pumpkin into small pieces, place it in a non-stick pan with a drizzle of oil and two cloves of garlic. Salt it lightly, add a freshly ground pepper and cook it over medium heat with a lid until it is soft (add a little water if necessary).
Remove the garlic and place the pumpkin in a mixer, reduce it to a cream with a little extra virgin olive oil and a little water until you obtain a velvety mixture with a not too liquid consistency.
In the same pan, sauté a few slices of red onion for 30 seconds.
Cook the hamburger on both sides. Brown the oil-free bacon in a non-stick pan until golden and crisp.
Heat the bread and make the sandwich: spread the pumpkin cream, arrange the burger, some onion rings, the bacon and some rocket leaves. Close the hamburger and serve immediately.