Preheat the oven to 350 degrees.  Spray a 9 x 13 baking dish with cooking spray and set aside.

In a large bowl combine the oats, flour, baking powder, and salt. Mix well and set aside.

In a medium bowl cream together the butter and brown sugar until fluffy.

Add in the eggs and vanilla and mix well.

Pour the butter mixture into the flour mixture and mix just until combined.

Carefully fold in the pecans.

Remove 1 cup of the mixture to use as the topping.  Add a little flour if it's not easy to crumble.

Spread the rest of the batter into the prepared pan.

Bake for 12 minutes.

Meanwhile, make the butterscotch mixture by combining the butter and brown sugar in a large saucepan over medium heat.  Stir occasionally or until the butter has melted and the brown sugar is combined with the butter.

Turn the heat up to medium high and bring the mixture to a low
boil.  Boil, stirring occasionally, for 4 or 5 minutes or until the
mixture has thickened.

Remove the mixture from the heat and add in the heavy.  Stir until combined.

Stir in the vanilla and butterscotch chips and mix until smooth.

Pour the butterscotch mixture over top of the partially baked
crust.  Sprinkle the topping evenly over top of the butterscotch mixture.

Bake for 30-35 minutes or until golden brown.

Remove from oven and cool completely on a wire rack. 

Cut into 24 squares and enjoy!