Add the flour, cornstarch, sugar, salt, and baking soda to a deep bowl. Whisk to blend.

In a small bowl or measuring cup, combine the cream and baker’s ammonia. Stir to dissolve. Add to the bowl with the flour, along with the vanilla extract and butter.

Using your hands (trust me on this, folks), stir the mixture together until it forms a scraggly looking dough. Continue to knead in the bowl until it comes together into a smooth dough. The whole thing transforms within a few minutes. Wrap the dough in waxed paper, or plastic film, and let rest in the fridge for 15 to 20 minutes.

Meanwhile, preheat the oven to 350ºF/180ºC. Line two rimmed baking sheets with parchment paper.

Remove the dough from the fridge, and break off a third of it. Place remaining dough back in the fridge if your kitchen is rather warm (my house does a fantastic job of retaining cold!). Place the bit of dough on a lightly floured surface, and roll it out to 1/8 to 1/4-thick. Using a round cookies, preferably a fluted one if you have it, cut out cookies. Transfer cookies to prepared baking sheet, leaving 1/4-inch space between each one.

Bake 10 to 12 minutes until golden around the edges. Use a spatula to transfer the cookies to a wire rack to cool completely. Repeat with the remaining dough.

Store cookies in an airtight tin or glass jar for up to 4 weeks, but good luck getting them to last that long if you have children.