Bring a pot of water to a boil. Add some salt.
Clean the Brussels sprouts by removing their outer leaves. Cut the tip of the stem using a small knife. Rinse the sprouts. Halve the sprouts if they are too large. Cut them from top to bottom so that each half still has half of the stem, which will help the leaves hold together. Leave the Brussels sprouts whole if they are small.
Boil Brussels sprouts: Place the sprouts into the boiling water, bring them to a boil again, and cook for about 7 minutes. The sprouts should be tender but not mushy. Drain well.
In the meantime, fry the bacon slices in a non-stick pan. There is no need to add any oil. Place on kitchen paper, which will help absorb the excess fat.
Fry sprouts: Add the well-drained sprouts to the pan, still containing the fat from the bacon. Fry for 2-3 minutes, stirring often.
Add the sliced garlic cloves and cook for 2 more minutes, constantly stirring, to avoid burning the garlic.
Serve: Remove the pan from the heat, crumble the bacon on top, and season with salt and freshly ground black pepper. Add the chopped parsley and serve.