Birthday Lasagna

INGREDIENTS

• Salt
• 1/2 cup chopped carrot
• Pinch freshly ground nutmeg
• 1/2 cup finely chopped onion
• 1/2 teaspoon chopped fresh oregano
• Splash red wine (optional)
• 1 cup beef stock or water
• 1 clove garlic, chopped
• 3 tablespoons all-purpose flour
• 1/2 package no-boil (or the equivalent in fresh) lasagna sheets
• 2 tablespoons olive oil
• 3/4 cups shredded fresh mozzarella
• 2 teaspoons all-purpose flour
• 1 1/2 cup whole milk
• 1 pound ground beef (85% lean)
• 3 tablespoons unsalted butter
• 1 1/2 cup canned chopped tomatoes, with their juices
• 1 teaspoon tomato paste