Start by preheating the oven to 180°C (350°F).
Grease and line an 8x8 inch or 9x9 inch square baking pan with greaseproof or baking paper and set aside.
Then start by washing, peeling, and chopping the apples into small cubes.
Place the apples into a medium saucepan, add the light brown sugar, vanilla, salt, cinnamon, and cornflour, and mix well.
Place over a low heat and cook for 10 minutes, stirring consistently, until the apples are fork-tender.
Once the apples are done, they should be shiny and almost jam-like. Set aside and allow to cool while we make the dough.
Next, cut the cold butter into small cubes.
In a large bowl, add the flour, sugar, and the cubes of butter.
Using your fingertips, press the butter into the dry ingredients until you have a crumble-like texture. (You could also do this by adding all of the ingredients into a food processor and pulsing until you have a crumble-like texture.)
Next, crack in the egg and, using a rubber spatula or wooden spoon, mix well until a dough forms.
Take ⅔ of the dough and press into the baking pan in an even layer.
Next, pour the cooled apple mixture over the dough layer and smooth out.
Finally, take the remaining dough and, using your fingers, crumble the dough evenly over the top of the apples, making sure that the apples are mostly covered.
Bake at 180°C (350°F) for 40-50 minutes, until golden brown.
Once baked, allow the bars to cool completely before cutting.
Run a sharp knife around the edge of the bars to help release them from the baking tray, then slice into squares.
Now simply serve and enjoy!!