Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a large mixing bowl, cream room temperature butter and brown sugar on medium speed for about 3-4 minutes until light and fluffy.

Add the eggs and vanilla extract to the creamed mixture and mix on low speed until well combined, about 1-2 minutes.

In a separate bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually mix this into the wet ingredients until just combined.

Gently fold in the grated zucchini using a spatula, ensuring it's well-distributed.

Stir in butterscotch morsels and pour the batter into the prepared baking pan, smoothing the top.

Sprinkle remaining butterscotch morsels on top and bake for about 40 minutes, until a toothpick comes out with a few moist crumbs.

Cool in the pan for 10-15 minutes, then transfer to a wire rack to cool completely before cutting into squares.