01 -
Turn your oven on to 375°F (190°C). Line a 9x13 inch pan with parchment, making sure the edges hang over for easier removal later.
02 -
Using a food processor, mix the flour, cold butter cubes, sugar, salt, vanilla, egg, and baking powder. Blend until the texture looks crumbly. No food processor? A fork or pastry cutter will do the job too.
03 -
Use half of the crumbly dough to press a compact layer into the bottom of your prepared pan.
04 -
Bake this base for about 12 minutes, just until it starts to set and turns barely golden. Take it out, but don't turn the oven off.
05 -
While your crust is baking, grab a big bowl and toss your apples with lemon juice, cinnamon, brown sugar, and cornstarch until everything's coated evenly.
06 -
Add the apple filling in an even layer on top of the slightly baked crust.
07 -
Take the rest of the crumb mixture and scatter it on top of the apples evenly.
08 -
Put it back into the oven and bake for 30-35 minutes, until the topping is a nice golden shade and the apples are bubbling near the edges.
09 -
Let it cool completely in the pan, then use the parchment to lift the bars out. Want clean slices? Stick it in the fridge for 2 hours before cutting.