Ginger Shortbread Cookies with Lemon-Cream Cheese Frosting

Make ginger shortbread cookies from 6 ingredients in a spring-like way. Look for crushed crystal ginger at your local grocery store in the bottled spice section.
Preheat the oven to 275 degrees. Beat the butter on medium speed with a powerful electric mixer until creamy; gradually add the sugar, whisking well. Add vanilla.Combine the flour, ginger, and salt; gradually add to the butter mixture, whisking on low speed until smooth after each addition.Place the dough on a lightly floured surface and roll out to a 1/4-inch thickness. Slice with a 2-inch round knife. Arrange 2 inches apart on 2 baking sheets lined with parchment paper (about 12 per sheet). Mash the scraps.Bake in batches at 275 ° C for 40 minutes or until the bottom is lightly browned. (Put the second portion in the refrigerator while the first one is baking.) Cool on a baking sheet for 2 minutes. Transfer to a wire rack and let cool completely (about 30 minutes).Meanwhile, prepare the lemon cream cheese frosting. Spread about 1 tablespoon on each cookie that has cooled, using a small spatula.