Start by adding the dairy-free butter and granulated sugar to a large bowl or stand mixer. Mix on low speed for about 3 to 5 minutes, scraping the sides of the bowl as needed. You want a light and fluffy mixture. Once it's smooth, add the non-dairy milk, vanilla extract, and if you choose, almond extract. Beat it again for about a minute until everything is well combined.
In another bowl, combine the all-purpose flour, cornstarch, baking powder, baking soda, and kosher salt. Gradually add this dry mixture to the wet ingredients while mixing on low speed. Stop mixing when just combined; the dough should be thick and not sticky. If it appears too dry, add more non-dairy milk by the tablespoon until it comes together.
Divide the dough in half and flatten each half into a disc. Wrap them tightly in plastic wrap and refrigerate for at least 2 hours or up to 3 days. Chilling is essential to prevent the cookies from spreading too much when baking.
When you're ready to bake, preheat your oven to 350°F (175°C) and line 2 to 4 baking sheets with a silicone baking mat or parchment paper.
On a lightly floured surface or silicone mat, take one disc of dough out of the fridge. If it's been chilled for over 3 hours, let it sit for 30 minutes to soften. Dust the surface and your rolling pin with flour, then roll the dough to about 1/2 inch thick. If the dough cracks, just pinch it back together and keep rolling.
Use your favorite cookie cutters to cut out shapes from the rolled dough. Press the cutter firmly down and give it a little wiggle to cut through completely. Transfer the cut cookies to the prepared baking sheets, leaving at least half an inch between each one.
Bake the cookies in the preheated oven. For cookies that are 4 inches or less, bake for about 8 minutes. Larger cookies will need 10 to 11 minutes. You want them to be just barely golden on the bottom. For crunchier cookies, bake a few minutes longer.
Once baked, let the cookies cool on the baking sheet for about 10 minutes before transferring them to a wire rack to cool completely. Repeat the process with the remaining dough and any scraps.
In a large bowl, sift the powdered sugar and mix in light corn syrup, pure vanilla extract, and 2 tablespoons of water. Whisk until smooth, adjusting the water for desired consistency. Add gel food coloring if you want to make colorful frostings.
Once the cookies are completely cool, transfer the frosting into piping bags and decorate as desired. Add sprinkles for that extra flair!
Allow the frosting to set for at least 3 hours before storing the cookies in an airtight container. They can last for up to 5 days, but they’re usually gone much faster!
