Sugar Cookies: In a medium bowl, whisk together flour, salt, and baking powder. In the bowl of an electric mixer fitted with the paddle attachment, beat together butter, sugar, and vanilla on medium-high speed until light and fluffy. Beat in egg, orange zest, and brandy until well combined. Add dry ingredients and mix on low speed until just combined. On a lightly floured surface, shape dough into a disk, wrap in plastic, and refrigerate until firm, at least 45 minutes and up to overnight.
Preheat oven to 350 degrees. Line two baking sheets with parchment. On a lightly floured surface, roll out dough to a scant 1/4 inch thick. Cut out shapes using a 3 1/2-inch fluted round. Use a 1-inch round cutter to cut out centers of cookies. Reroll scraps once (you should have about 16 cookies). Transfer both wreaths and cookie centers to prepared sheets, spaced about 1 inch apart. Refrigerate until firm, at least 1 hour. Bake until set and golden around edges, 15 to 20 minutes. Transfer sheets to wire racks and let cool completely.
Glaze: Whisk together confectioners’ sugar, egg white, and 1 teaspoon lemon juice until smooth. If necessary, add remaining 1 teaspoon lemon juice to reach desired consistency. Glaze should be opaque but not too thick as to run down the edges of the cookie once dipped. If not using immediately, glaze can be stored at room temperature, with plastic wrap pressed directly on surface, up to 2 days, or in refrigerator up to 3 days. Bring to room temperature before using.
Working with one cookie at a time, dip cookie top-side down in glaze to coat surface, allowing excess glaze to drip back into bowl. If glaze runs down sides of cookie and is too transparent, add more confectioners’ sugar, 1 tablespoon at a time. If glaze is too thick, add water, 1 teaspoon at a time. Transfer glazed cookies to a wire rack or baking sheet. Working quickly before glaze sets, decorate cookies with toppings, if desired. Let stand at room temperature until completely dry, at least 2 hours. Cookies can be stored in an airtight container at room temperature overnight.