Line a 8” pie dish (or cake tin) and butter or grease it well.
Put the flour, sugars, baking powder, salt, cinnamon and nutmeg into a large mixing bowl. Whisk together and then mix in thediced apple and walnuts so they’re well coated with the flour.
Mix in the egg and vanilla extract. If the batter feels too dry mix in a little milk, a teaspoon at a time. Don’t add too much milk because this batter should be stiff and not like typical cake batter.
Scrape the batter into the prepared tin and level it. Bake at 180C (350F) for about 30 minutes till the pie puffs up slightly and is brown.
Remove from oven and cut into wedges while still warm. Serve as is with coffee or tea, or with ice-cream or whipped cream.