Prepare streusel topping;
In a small bowl, mix together flour, brown sugar, oats, salt, and cinnamon.
Cut in butter until mixture resembles coarse crumbs. Set aside.
Prepare your favorite pancake recipe or use your favorite boxed pancake mix, prepared per directions on box.
Add diced apple to pancake batter. Stir well, let batter sit for 5 to 10 minutes.
Heat griddle to 350° F. Spray with a non-stick cooking spray. Ladle pancake batter onto hot griddle.
Turn pancakes over when surface bubbles appear, flip over and cook until golden brown.
To serve: Place hot pancakes on oven-proof plate, sprinkle with streusel topping.
Set oven to broil, place stack of pancakes on oven rack, 6 inches under broiler, broil for 1 to 3 minutes or until brown sugar and butter melt. Watch carefully!
Serve with maple syrup and extra chopped apples.