With a mixer on medium speed, beat the butter, powdered sugar, and vanilla extract until fluffy.

Beat in the flour just to form a dough. On slow speed, add in the mini chocolate chips.

Put the dough into a gallon-sized plastic bag, or place between two layers of plastic wrap.

Flatten the dough down with your hands, then roll it into a rectangle shape ¼-inch thick. Even off the edges to a rectangle.

Chill it flat in the refrigerator for 1 to 2 hours.

Preheat the oven to 325 degrees.

Line a cookie sheet with parchment paper.

Use a scissors to remove the top piece of the plastic bag.

Use a heavy knife and cut the dough into rectangles or squares.

Place the cut pieces on the prepared cookie sheet.

Bake for 15-18 minutes, or until the edges are a light brown.

Transfer the cookies to a wire rack and let them cool.