Preheat oven to 180 degrees Celcius.
Add the butter and brown sugar to a large mixing bowl. Beat at medium speed until creamy.
Add eggs and vanilla, mixing until combined, about 1 minute.
Add flour, baking powder and salt, mix until well combined. Fold in mini chocolate chips.
Shape into 2 10" x 2" logs and place on a lined or greased baking sheet.
Bake 22 to 25 minutes. Remove from oven and allow to cool 30 minutes.
Lower oven temperature to 150 degrees Celcius.
Slice logs into about 1/2 inch slices and place on cookie sheet. Each log will make about 18-20 slices. Bake 15 minutes. Flip slices over and bake an additional 15 minutes.
Remove to a wire rack to cool. Store in an airtight container.