Preheat the oven to 350°F (175°C). Line a baking sheet with parchment like a responsible adult.
Stir flaxseed and water to make your flax egg. Let it thicken like your last situationship.
Whisk flour, salt, baking soda, and espresso powder in one bowl.
In another, cream vegan butter and both sugars until it looks like sweet velvet.
Add the flax egg and vanilla, mix well.
Combine dry ingredients into the wet mix. Stir like your life depends on it.
Fold in chocolate chips with dramatic flair.
Scoop dough, flatten slightly, and bake 10–12 minutes until golden and smug.
Meanwhile, whisk milk, espresso, cornstarch, maple syrup, and salt in a saucepan over medium heat.
Stir constantly until thick, like creamy gossip. Remove from heat, stir in butter and vanilla.
Let custard cool and thicken further. Chill if needed.
Once cookies are cool, sandwich custard between two. Or eat solo, no judgment.