-In a large bowl, mix the 1/2 cup sugar, 1/4 cup flour and the cinnamon.
Add the Apples, toss to combine thoroughly . Set aside while you make the crust.
Prepare the Crust:
-In medium bowl stir together 2 cups flour, 1/2 cup sugar, and baking powder.
Cut in butter with a pastry cutter, until looks like wet sand.
Stir in beaten egg with fork.
(note, you can also do this with a Food Processor... just don't over process it! Pulse till you have sand, then a few more pulses after adding the egg)
Dump about 2/3 of the dough into the baking pan. Press evenly and firmly into pan.
Lay the apple slices over the crust. Spend a few minutes, lay to them out neatly. I make long rows down the length of the pan... keeps it looking nice, and makes slicing a lot easier.
(Sprinkle any remaining flour/sugar/cinnamon stuff from the bowl over the apples)
Take the other 1/3 of the dough and crumble it over the apples. I grab it in my fist and sprinkle it through my fingers, making small and big lumps evenly over the apples. This makes the Streusel.
Bake 45 minutes.. until beginning to brown
Cool on rack for 1 hour.
Now you get to choose:
You can sprinkle powdered sugar over the cake and serve it...
Or
You can make a thick glaze by combining the powdered sugar and a few spoonfuls of milk... make sure it's not too thin... less milk is better...pour the glaze over the cake, let sit a bit, cut and serve
Or
You can eat it plain.
No matter which you choose, it will be delicious! Top it with whipped cream and it's bliss.
Notes
This recipe makes bar type apple streusel cake squares... Use a 9 x 12 inch Brownie Pan. And it travels fairly well!