Two Whole Roasted Chickens + Chicken Gravy

Bahan-bahan (12 porsi)

• 2 whole chickens (5 lb each) (giblets removed, patted dry)
• 5 tsp fine sea salt (divided)
• 2 tsp ground black pepper (divided)
• 4 Tbsp unsalted butter (melted)
• 1 large lemon (quartered)
• 1 g arlic head (halved crosswise)
• 4 rosemary sprigs (divided)
• 2 medium onions (sliced to 1/4” thick rings)
• 1 tsp olive oil
• 4 Tbsp oil (skimmed from pan drippings )
• 2 Tbsp all-purpose flour
• 1 cup liquid drippings
• 1/2 cup water or milk (added to taste and desired consistency)