⅓ cup (60 g) of butterscotch chips (chopped walnuts and chocolate chips are equally tasty)
Method
Preheat the oven to 350°F (175°C). Lightly butter and flour an 8X8-inch pan (20 cm x 20 cm). Whisk together the melted butter and sugar in a bowl.
Add the egg and vanilla extract and whisk.
Add the flour, baking soda, baking powder, and salt, mix it all together. Add the butterscotch chips or other mix-ins.
Pour into the pan and spread evenly. Bake for 25-30 minutes or until a tester inserted into the center comes out clean. Allow to cool. Cut into squares or rectangles and serve.