Butternut Squash Lasagna

Ingredients

• 4 1/2 pounds butternut squash
• 4 cloves garlic
• 1 tablespoon olive oil
• 1 teaspoon lemon juice
• salt to taste, for sauce
• 1 5/16 pounds celeriac
• vegetable broth
• 2 cups butter beans or any white bean
• nutmeg grated to taste
• 1 teaspoon lemon juice
• 1 tablespoon olive oil
• 1 pinch salt if needed, for bean "béchamel"
• 1/2 cup water