Lasagne alla Bolognese al Forno

Ingredients

• 5 cloves garlic
• 2 medium onions
• 4 ribs celery
• 2 carrots
• 1/4 cup olive oil
• 1 lb ground veal
• 1 lb ground pork
• 4 oz pancetta
• 1 cup dry white wine
• 1 cup whole milk
• 6 oz tomato paste
• 1 tsp fresh thyme leaves
• 5 tbsp unsalted butter
• 1/4 cup all-purpose flour
• 3 cups whole milk
• 1 to 2 tsp sea salt
• 1/2 tsp grated nutmeg
• 3 qt water
• 1 tbsp sea salt
• 1 cup packed, fresh spinach leaves (3.5 ounces)
• sea salt (to taste)
• freshly ground black pepper (to taste)
• 3 1/2 cups all-purpose flour, plus extra (for kneading)
• 5 large eggs