Beat the butter, sugar, and vanilla (if using) with a mixer on medium speed until pale and fluffy, about 2 minutes.

Mix in the flour, salt, and strawberry powder on low just until the dough comes together, about 30 seconds.

Roll the dough into a 2-inch-wide log on parchment paper, wrap tightly, and chill at least 1 hour.

Heat oven to 350°F (175°C). Slice the log into 1/4-inch rounds, place on a parchment-lined baking sheet, and bake 12 to 14 minutes until set. Cool on the pan for 5 minutes, then move to a wire rack.