Slow Cooker Buttermilk Mashed Potatoes

lbs. yukon gold potatoes, peeled and chopped into 1″ cubes

low sodium chicken stock (may substitute with vegetable stock)

large cloves garlic, smashed

salt, plus more to taste

low fat buttermilk, warmed slightly (not hot) (I used 1 1/4 cups)*

unsalted butter, softened

freshly chopped rosemary