Peel and cut the chayote in small cubes. In a pot heat some oil and sweat the leeks. Then add the chayote and potato and continue cooking. Then add the stock and cook until all vegetables are cooked. Blend and finish with cream and seasoning to taste. For the roasted ricotta, slice the ricotta in flat pieces. Put on a baking sheet, drizzle with olive oil, seasoning and fresh thyme. Bake in oven at 180⁰c until golden colour. Serve pieces of roasted ricotta in the chayote soup and drizzle with lemon oil.