Preheat oven to 375°F (190°C). Line baking sheets with parchment paper or silicone mats. Set aside.
In a large bowl, whisk together sugar, ginger, nutmeg, cinnamon, salt, and baking soda.
Add softened butter, evaporated milk, and molasses. With an electric mixer, start on the lowest speed so that the liquid doesn’t splash out of the bowl. Gradually increase the speed until the butter and sugar are creamed together and completely smooth.
With the mixer on low speed, gradually add 4 cups of flour (one cup at a time), mixing until the flour is incorporated.
The dough should be stiff enough to handle without sticking to your fingers, so if it’s still too wet and sticky, add additional flour (½ cup at a time), just until a fairly stiff dough comes together.
When the dough is smooth, roll it out to ½-inch thickness on a very well-floured surface.
Use a 2 ½-inch round biscuit cutter (or other cookie cutter) to cut the dough into round shapes. Continue to add as much flour as necessary to the dough, the rolling pin, and the cookie cutters to prevent the dough from sticking. Place shapes onto prepared baking sheets.
Bake for 10-12 minutes, or until slightly golden brown but still soft. Make sure that you don't bake them for too long or they will become hard and crispy. To maintain the soft, chewy, cake-like texture, pull them out of the often while they're still soft and let them firm up slightly while they cool.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.