Preheat the oven to 375°F/190°C. Line a baking sheet with parchment paper and set aside.
Melt the sugars. In a small pot on the stove over medium-low heat, combine the white sugar, brown sugar, molasses, and water. Whisk together until the sugars have melted, but don’t bring this to a rolling boil. Set aside to cool slightly.
Make the flax egg. While the sugar mixture is cooling, in a separate small bowl, combine the flaxseeds with the hot water. Whisk and set aside to gel up for 5 minutes.
Make the dough. Transfer the sugar mixture into a large bowl or the bowl of your stand mixer. Add the spices: Cinnamon, ginger, cardamom, allspice, cloves, black pepper, and salt. Whisk to combine. Add the flax egg and mix well again. Add the vanilla and heavy cream. Finally, add the flour and baking soda and mix until the dough is combined. It will be soft and a bit tacky but not overly sticky. You can add a few spoonfuls of flour if your dough is very wet.
Roll the cookies. Using a 1 tablespoon scoop, roll the cookies between your hands to get cookie dough balls. You should get 23 to 24 cookies. Optional: You can chill the cookies now for up to 24 hours.
Bake the cookies. Bake the cookies on one cookie sheet for 12 to 14 minutes. The cookies will be set and have puffed up slightly. Remove from the oven and do not touch them - let them cool on the hot tray for an hour.
Frost the cookies. After the cookies have cooled, it’s time to frost. Combine the powdered sugar and water in a bowl until a thick icing is made. Dip the top of each cookie into the frosting. Place the cookies on a wire rack to allow for any drips. Serve and enjoy!
