Gratin Potatoes with Spinach and Cheddar - Yummy Expert

Ingredients

• 6 medium-sized potatoes, sliced thinly
• Salt, to taste
• Water, enough to cover the potatoes
• 1 onion, finely chopped
• 1 garlic clove, finely chopped
• 2 red pepper, chopped
• 3 sprigs of spinach
• 2 tbsp vegetable oil
• 1 tbsp butter
• 2 tbsp flour
• 500 ml milk
• Pepper, to taste
• Nutmeg, a pinch (optional)
• 1 tbsp olive oil
• Cheddar cheese, grated (enough for layering and topping)