Preheat oven to 190°C or 170°C fan. Combine egg yolks, milk and flour. Set aside.
Using an electric beater or balloon whisk, beat eggwhites until soft peaks form. Gently fold eggwhites into yolk mixture, using a large metal spoon.
Heat olive oil in a large ovenproof frying pan on low. Pour in egg mixture. Bake omelette for 6 minutes, until puffed and golden. Slide onto a heated serving dish. Spread ricotta over half of omelette and top with ham and asparagus. Fold omelette over to enclose filling. Cut into wedges or thick slices to serve if you like.