In a large mixing bowl, combine softened unsalted butter and granulated sugar. Beat until light and fluffy, about 3-4 minutes.

Add a large egg and vanilla extract. Beat on low speed until fully combined, about 1-2 minutes.

In a separate bowl, whisk together all-purpose flour, baking powder, and salt. Gradually mix into the wet ingredients until a soft dough forms.

Fold in mini chocolate chips or your chosen add-ins using a spatula.

Divide the dough into two equal halves and shape each piece into a log about 2 inches in diameter. Wrap in plastic wrap and refrigerate for at least 2 hours.

Preheat your oven to 350°F (175°C) 15 minutes before baking. Line baking sheets with parchment paper.

Unwrap the chilled dough logs and slice into 1/4-inch thick rounds. Arrange on baking sheets.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden.

Cool on baking sheets for a few minutes, then transfer to wire racks to cool completely.