Preheat the oven to 350 degrees F and prepare your baking trays, either lining them with the silicone mats or parchment paper.
Combine the flour, cocoa powder, baking soda, baking powder, and salt in a mixing bowl and whisk to fully combine.
Add the plant-based milk, flaxseed, oil, sugar, vanilla, and espresso to the bowl of your standing mixer (if using) or a separate bowl and mix to combine. Beat the wet ingredients on a low speed until the sugar is dissolved, about 3-5 minutes.
Slowly add in the dry ingredients, about 1/4 cup at a time, keeping the speed low. This will make a fairly wet dough. Don't overbeat it, just mix until there are no streaks of dry ingredients remaining.
Fold in the white chocolate chips.
Use the cookie scoop or about a tablespoon of batter per cookie to place 12 cookies per baking sheet, evenly spaced. Bake for 8 minutes then remove and let cool on the tray for another 5 minutes, then move to a wire rack to cool.
Cookies can be enjoyed immediately, stored in an airtight container for up to a week, or frozen for up to a month.