Set a heavy skillet (preferably cast iron) over medium heat and cook the bacon until it gets nice and crispy.
Meanwhile, cut the cauliflower into little florets and add it to the bowl of your food processor. Process on pulse until the cauliflower has the texture of coarse gravel; you may want to work in 2 to 3 batches so to not overcrowd the bowl. Transfer the cauliflower to a large mixing bowl.
Add the rest of the ingredients, including the bacon (leave the fat in the pan, though) and mix with a large spoon until well combined.
Place the skillet (with the bacon fat in it) back over the heat source. Set that knob to medium and, when the pan is hot enough, carefully drop about 1/2 of a cup of mixture for each rösti. If you can, pack that mixture real good before to drop it in the pan. Then, shape the röstis directly in the pan and press them lightly with a spatula to help them stick together.
Cook the röstis for 3 to 4 minutes, until a golden crust develops, then carefully flip the fritters with a spatula, supporting them with your free hand as you flip them and cook for 2 to 3 minutes.
You will have to cook the röstis in 3 or 4 batches, depending on the size of your pan. Add ghee (or other cooking fat of your choice) to the skillet and let it come up in temperature between each batch.
Keep the cooked röstis in a warm oven while you work on the others.