Make the tart dough: Using a pastry blender or 2 knives, combine the flour, butter, salt, and pepper until mixture resembles coarse meal.
Using a fork, mix in 2 tablespoons of the oil and the water just until the bottom of the mixture begins to cling together. If necessary, add an additional tablespoon of oil.
Gather into a ball, flatten into a disk, wrap in plastic wrap, and chill for 30 minutes.
Bake the tart: Preheat oven to 200°C. Roll out the chilled dough into 7cm circles and place in a muffin tin; set aside.
Combine the Camembert, ham and walnuts in a bowl. Fill each tart shell and place in the oven to bake until golden. Serve warm.
