Preheat your oven to 350°. Spray or rub butter in a 9x13 pan.
In a bowl mix together your pancake mix, sugar, milk, oil and egg. Stir until well incorporated.
Pour the batter into your 9x13 pan.
In a smaller bowl, mix together your oats, brown sugar, cinnamon and softened butter until you have a crumbly topping. Sprinkle on top of the batter.
Bake in the oven for 20-25 minutes until your coffee cake is done in the middle. You can insert a knife to check if it is done.