Best Pastitsio Recipe - How to Make Homemade Pastitsio

Ingredients

• 2 tbsp. extra-virgin olive oil
• 1 yellow onion, chopped
• 3 cloves garlic, finely chopped
• 2 tsp. kosher salt, divided
• 1 1/2 lb. ground beef
• 1/4 c. tomato paste
• 1/2 c. red wine
• 1 (28-oz.) can crushed tomatoes
• 1 1/2 c. low-sodium beef stock
• 1 bay leaf
• 1/2 tsp. ground cinnamon 
• 1/4 tsp. ground cloves
• Cooking spray
• 12 oz. bucatini
• 2 tbsp. plus 1 tsp. kosher salt, divided
• 4 oz. feta, crumbled
• 2 large eggs, separated
• 1/2 c. (1 stick) unsalted butter
• 1/2 c. all-purpose flour 
• 3 c. whole milk
• 1/2 tsp. ground nutmeg
• 8 oz. Kefalotyri or Pecorino Romano cheese, finely shredded, divided