Preheat the oven to 350°F. Grease a 9x13-inch baking pan or line it with parchment paper for easy removal.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
In a large bowl, combine the melted butter, brown sugar, and granulated sugar. Mix until well combined. Add the eggs and vanilla extract, and stir until smooth.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the grated zucchini and butterscotch chips.
Pour the batter into the prepared baking pan and spread it evenly. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Allow the bars to cool in the pan for about 10 minutes before transferring them to a wire rack to cool completely. Cut into squares and serve.