Homemade Greek Moussaka with Creamy Béchamel Topping

Ingredients

• 2 lbs eggplants, cut into 3/8" thick slices
• 4 yellow potatoes, cut into 3/8" thick slices
• Enough vegetable oil for frying
• 2 tbsp olive oil
• 2 red onions, finely diced
• 2 cloves garlic, crushed
• 2 lbs ground beef
• 1 tsp sugar
• 1 tsp kosher salt
• 1/2 tsp ground cinnamon
• 3 tbsp tomato paste
• 400g (14 oz) diced tomatoes
• 240ml (1 cup) dry red wine
• 1 bay leaf
• 60g (1/4 cup) butter
• 80g (1/3 cup) all-purpose flour
• 600ml (2 1/2 cups) whole milk at room temp
• 1/4 tsp kosher salt
• 1/4 tsp ground black pepper
• 1/8 tsp ground nutmeg
• 75g (3/4 cup) freshly grated Parmesan
• 2 egg yolks