Kabocha Gratin

Bahan-bahan (8 porsi)

• 1½ lb kabocha squash ((½ kabocha))
• 1 clove garlic
• ½ onion ((4 oz, 114 g))
• 9.5 oz king oyster mushrooms (eringi) ((1 package))
• 3.5 oz shimeji (brown beech) mushrooms ((1 package))
• 1½ Tbsp extra virgin olive oil
• 1½ Tbsp miso
• 1 cup water
• Diamond Crystal kosher salt
• freshly ground black pepper
• 1 Tbsp unsalted butter ((to grease the baking dishes))
• ½ cup Gruyere cheese ((freshly grated))
• ¼ cup panko (Japanese breadcrumbs) ((4 Tbsp))
• 2 Tbsp Diamond Crystal kosher salt
• 1½ cups uncooked elbow macaroni ((6 oz; makes 3 cups cooked macaroni))
• 4 Tbsp unsalted butter
• ½ cup all-purpose flour (plain flour)
• 3⅓ cups whole milk ((warm))
• Diamond Crystal kosher salt ((to taste))
• ⅛ tsp white pepper powder ((to taste; or substitute freshly ground black pepper))
• ¼ tsp freshly grated nutmeg ((to taste; optional))
• chives or parsley ((minced))