Slow Cooker Cheesy Garlic Herb Mashed Potatoes

Bahan-bahan (8 porsi)

• 4 pounds yukon gold potatoes, peeled and quartered
• 3 cups heavy cream
• 1 cup whole milk
• 8 fresh sage leaves, plus more for serving
• 3 sprigs fresh thyme, plus more for serving
• 4 cloves garlic, smashed
• 1 parmesan rind ((optional) )
• 6 tablespoons salted butter, at room temperature
• kosher salt and black pepper
• 1 cup shredded gruyere cheese ((or use more!!))