Mix the plant milk and vinegar in a jar or bowl until well combined. Let the mixture rest at room temperature for at least 5 minutes. After this time, the milk will thicken and curdle.
Add the vegan butter, sugar, vanilla extract, and almond extract to an electric mixer bowl and beat until light and fluffy. You could also use a regular large bowl and a hand mixer.
Incorporate all the remaining ingredients (except the vegan royal icing) and mix until well combined.
Divide the dough in half and roll into 2 balls. Place each ball onto a piece of lightly floured parchment paper. With a lightly floured rolling pin, roll the dough out to about ¼-inch thickness (about 0.6 cm).
Sprinkle a little flour on top of one of the rolled-out doughs. Place a piece of parchment on top to prevent sticking and then place the second rolled-out dough on top. Finally, cover with plastic wrap and refrigerate for at least 1 hour or overnight.
Preheat the oven to 350ºF or 180ºC.
Line 2-3 baking sheets with parchment paper. Remove the dough from the fridge, and using a cookie cutter, cut the dough into shapes. Then re-roll the remaining dough and continue cutting until all is used.
Bake for about 8 to 12 minutes or until the cookies are lightly golden brown. Be careful so they don't get burnt!
Remove from the oven and allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a cooling rack to cool completely before decorating.
Decorate the cooled cookies with the vegan royal icing (this step is optional). Decorate the cookies directly on a baking sheet so you can stick the entire baking sheet in the refrigerator to help speed up the icing setting. You can also leave the decorated cookies at room temperature to set, but it will take longer, especially during the hot months.
Serve your vegan sugar cookies immediately.
Keep the leftovers in an airtight container for about 1 week or in the freezer for up to 3 months.