Preheat oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone mats.
In a large bowl, beat together softened butter, cane sugar, and brown sugar until light and fluffy.
Mix in the eggs, one at a time. Then add sourdough starter and vanilla extract. Stir until smooth.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add dry ingredients to the wet ingredients, mixing until just combined.
Gently fold in the chocolate chips or chunks until evenly distributed.
Scoop dough and chill in the fridge for 30 minutes to 1 hour for best results.
Place onto prepared baking sheets, spacing them 2 inches apart. Bake for 10-12 minutes or until edges are golden brown and centers are slightly underbaked for a gooey texture.
Let the cookies cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely. Then Enjoy!