To make the base crust: In a large bowl, use a mixer to cream butter and brown sugar until light and fluffy. Add rolled oats, flour, vanilla, baking powder, and salt. Mix until mixture resembles coarse crumbs.
Transfer the mixture into a 9 x 9 inch baking pan, and firmly press it down to create an even layer. Spread cranberry sauce on top.
To make the topping: In a medium saucepan, melt 3 tablespoons of butter over medium heat. Once melted, remove from heat and stir in the brown sugar, rolled oats, pecans, and cinnamon. Stir until fully combined. Sprinkle the topping on the cranberry sauce layer.
Bake for 30 to 35 minutes until lightly browned. Place on a wire rack to cool. Once the pan is cool, cut into squares and enjoy!