Preheat your oven to 325°F (160°C).

Line a baking sheet with parchment paper.

In a medium bowl, whisk together the flour, powdered sugar, and salt.

In a large bowl, cream the softened butter until smooth and fluffy.

Stir in the vanilla extract (if using).

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix! The dough should be crumbly but hold together when pressed.

Choose your shaping method: Classic Slab, Cut-Out Cookies, or Round Cookies.

For Classic Slab: Press the dough evenly into an 8-inch square baking pan. Use a fork to prick the surface of the dough all over. Cut into squares or triangles before baking.

For Cut-Out Cookies: Lightly flour a clean surface and roll out the dough to about 1/4-inch thickness. Use cookie cutters to cut out desired shapes. Place cookies on the prepared baking sheet.

For Round Cookies: Divide the dough in half and roll each half into a log about 1.5 inches in diameter. Wrap the logs in plastic wrap and chill in the refrigerator for at least 30 minutes. Slice the logs into 1/4-inch thick rounds and place them on the prepared baking sheet.

Bake for 20-25 minutes, or until the edges are lightly golden brown.

Let the shortbread cool completely on the baking sheet before handling.

Decorate as desired: Sprinkle with granulated sugar before baking, drizzle with melted chocolate once cooled, or add sprinkles.