1. Combine butter and sugar in a large bowl and beat with an electric mixer on medium until light and fluffy, 3 to 5 minutes, scraping down bowl halfway through. Add egg yolks and vanilla and beat until combined, about 30 seconds.
2. Scrape down sides and bottom of bowl, then add flour, salt, and nutmeg (if using) and mix on low until dough just comes together, about 30 seconds. Turn dough out onto counter and divide in half. Flatten each piece into a 6" disc, then wrap in plastic and refrigerate 30 minutes.
3. Center a rack in oven and heat to 375 degrees. Line a baking sheet with parchment and set aside.
4. Working with one disc at a time, unwrap dough and place on a lightly floured surface. Roll to a 1/4" thickness, then use cookie cutters to cut out shapes. Transfer to prepared baking sheet, spacing cookies at least 1" apart.
5. Bake until edges of cookies are golden brown, 10 to 14 minutes, rotating pan halfway through. Cool cookies on baking sheet for 5 minutes, then transfer to a wire rack and cool completely. Repeat with remaining disc.
For sandwich cookies, follow master cookie recipe, but roll dough slightly thinner (between 1/8" and 1/4" thick) and start checking for doneness after 8 minutes. When completely cool, sandwich jam, lemon curd, chocolate-hazelnut spread, or the filling of your choice between cookies, then roll edges in granulated sugar if desired; let set at least 30 minutes.
For slice-and-bake cookies, after mixing and halving dough in Step 2, form each half into a 2"-wide log. Wrap logs in parchment, twisting ends to seal, and refrigerate until firm, about 1 hour. Working with one log at a time, use a sharp chef's knife to slice dough into 1/4"-thick discs, rolling log as you go to retain shape. Arrange cookies 1" apart on a parchment-lined baking sheet and bake until golden brown, 10 to 14 minutes, rotating pan halfway through. (If desired, brush outside of log with one egg yolk beaten with 1 tablespoon water and roll in demerara sugar before slicing.)
For glazed cookies, mix 1 cup confectioners' sugar with 2 tablespoons of liquid (such as orange or grapefruit juice, rose water, apple brandy, or a combination of milk and a dash or two of any flavored extract) in a shallow bowl until a thick but pourable glaze forms, adding more liquid one teaspoon at a time as needed to reach desired consistency. Dip tops of fully cooled cookies in glaze, allowing excess to drip off. Return to wire rack and decorate with sprinkles, chopped nuts, or candies if desired; let set at least 30 minutes.
For thumbprint cookies, after mixing dough in Step 2, immediately roll heaping tablespoons of dough into balls (about 1?1/2" in diameter) and place 2" apart on a parchment-lined baking sheet. Flatten balls into 1/2"-thick discs, then use the back of a rounded teaspoon measure to make an indentation in center of each disc, smoothing any cracks that form with damp fingers. Bake 10 minutes, then remove baking sheet from oven, reform indentations, and fill each with 3/4 teaspoon jam. Rotate pan and continue to bake until cookies are golden brown, 8 to 12 more minutes. Cool 30 to 45 minutes.
Source: Hannaford fresh Magazine, December 2019