Instructions:
To make cookies: In a small bowl whisk together flour, baking powder and salt until thoroughly combined. Set aside. With a mixer, cream together butter and sugar until it is light and fluffy, about 3 minutes. Scrape down sides of bowl with a rubber spatula as needed. Mix in and egg and vanilla. Add dry ingredients and beat at low speed until just combined.
 
On a floured work surface shape the dough into a 9 x 2 inch log. Wrap tightly in plastic wrap and refrigerate until firm, 4 hours or overnight.

Position rack in middle of oven. Preheat oven to 375ºF.

Lightly butter a large baking sheet. Cut the log into 30 slices, about ¼ inch thick. Arrange cookies on prepared baking sheet, spaced about 2 inches apart. Bake 10 minutes, rotating halfway through cooking, until the edges are lightly browned. Cool cookies on baking sheet for 1 minute then transfer to a wire rack to cool completely. Cookies can be made ahead and frozen until ready for assembly.
 
To assemble sandwiches: Remove ice cream lid and let container stand at room temperature to soften 10-15 minutes, stirring occasionally to encourage even softening. Place a scoop of softened ice cream between two cookies and gently press together. Roll the edges in desired garnish.

Place sandwiches on a tray and freeze, covered, until they are firm. Sandwiches may be stored for up to 2 days.

Makes 15 sandwiches

Note: Ice cream sandwiches can also be made with purchased sugar cookies.