In a mixing bowl, beat the butter and sugar together at medium speed for 2 minutes until creamy and smooth.

Add the egg, vanilla extract, and optional almond extract; mix on low speed until combined.

In a separate bowl, whisk together the flour, salt, and baking powder; gradually fold into the butter mixture until no flour is visible.

Fold in the optional add-ins of your choice.

Divide the dough and shape each half into 9-inch logs, about 1.75 to 2 inches thick. Roll logs in coarse sugar if desired.

Wrap each log tightly in plastic or parchment and refrigerate for at least 2 hours or freeze for 30 minutes and then refrigerate for another hour.

Preheat oven to 350°F (177°C) and line baking sheets with parchment paper.

Slice the chilled logs into 1/4-inch rounds, rotating the log each time for even cuts.

Bake for 12 to 14 minutes, until the edges are lightly golden and the centers are set.

Cool on baking sheets for 3 minutes before transferring to a wire rack to cool completely.