Preheat
oven to 350 degrees F. Melt 1/4 cup butter in a 9 inch
square pan in the oven. Remove and add the brown sugar
and lemon juice. Arrange apples on top of the sugar
mixture.
Mix
flour, baking powder, salt, cocoa and sugar together
in a medium bowl. Cut in butter until mixture looks
like fine bread crumbs.
Beat
milk, egg and vanilla together with a fork and add to
the dry ingredients. Stir just enough to blend. Spoon
over the apples and spread evenly.
Bake
for about 40 minutes, until a toothpick inserted in
the centre comes out clean.
Set
on a rack and allow to cool for 5 minutes, then turn
upside down onto a serving plate. Let it sit for 2 or
3 minutes so that all the syrup mixture and apples drop
out. Serve warm.