Tater Tot Casserole Hotdish - Alas, A Website

Ingredients

• For the Mushroom Sauce:
• 5 cups (570g) button mushrooms, washed, dried, and quartered
• 2 tablespoons (30ml) extra-virgin olive oil
• 12 sprigs thyme, divided
• Kosher salt and freshly ground black pepper, to taste
• 2 1/4 cups (450g) whole milk
• 1/2 onion (125g), peeled and roughly chopped
• 2 cloves (8g) garlic, smashed
• 2 tablespoons (28g) unsalted butter
• 3 tablespoons (25g) flour
• For the Ground Beef:
• 1 tablespoon (15ml) vegetable oil
• 1 pound (454g) 90% lean ground beef
• 1 small (250g) onion, diced
• 2 cloves (8g) garlic, finely minced
• 1 tablespoon (8g) all-purpose flour
• 3/4 cup (180ml) chicken stock, either homemade or low-sodium store-bought
• 3/4 cup (100g) frozen or fresh peas
• 3/4 cup (100g) frozen or fresh corn kernels
• 1/4 cup (30g) chopped parsley
• 1/4 cup (30g) chopped chives
• 1 tablespoon (15g) Dijon mustard
• 2 teaspoons (10ml) Worcestershire sauce
• To Finish:
• 1 pound (454g) Tater Tots, frozen or homemade
• Ketchup, for serving