Cook bacon with butter until slightly crispy. Set bacon aside on a paper towel-lined plate.
Using the same pan, cook onions and garlic with 1/2 teaspoon of salt until soft, about 8 minutes.
Cut the cabbage in half and discard the core. With the flat cut-side down, slice it as thinly as possible as though you were making coleslaw.
Add the cabbage, 1 teaspoon salt, and pepper. Saute for 10-15 minutes, stirring occasionally, until the cabbage is tender and begins to brown.
Add bacon. Season to taste and serve warm.