Sloppy Joe Casserole

Bahan-bahan (6 porsi)

• 2 ½ pounds Yukon Gold potatoes (peeled and cut into 1-inch pieces)
• 4 cloves garlic (peeled)
• 2 teaspoons kosher salt (plus additional to taste)
• ¾ to 1 cup buttermilk (or regular milk)
• 1 tablespoon extra virgin olive oil
• 1.5 pounds lean ground beef (90/10)
• 1 ½ teaspoons kosher salt (divided)
• 1 large ellow onion (finely chopped (about 1 ½ cups))
• 1 large red bell pepper (¼-inch diced (about 1 ½ cups))
• 3 medium carrots (¼-inch diced (about 1 ½ cups))
• 3 cloves garlic (minced)
• 2 ½ teaspoons chili powder
• 2 tablespoons tomato paste
• 1 cup low-sodium beef (or chicken broth or water)
• ½ cup ketchup
• 2 tablespoons Worcestershire sauce
• 2 tablespoons Dijon mustard
• 1 ½ tablespoons brown sugar
• 2 teaspoons red wine vinegar
• 1 cup shredded cheddar cheese
• 2 g reen onions (thinly sliced, for topping)