Preheat oven to 350°F (175°C), line a baking sheet like a boss.
Mix flaxseed meal and water. Let it sit and thicken while you pretend to clean.
In a big bowl, cream vegan butter, white sugar, and brown sugar until fluffy enough to flirt.
Stir in vanilla, espresso powder, and the flax egg.
Mix flour, baking soda, and salt in another bowl. Combine with wet ingredients until a dough forms.
Fold in those glorious chocolate chips.
Scoop tablespoon-sized dough onto baking sheet. Leave space—they will spread like gossip.
Bake for 11–12 minutes until golden around the edges and still soft in the middle.
Cool cookies completely or risk a cream meltdown.
For the filling, beat vegan butter, powdered sugar, espresso, vanilla, milk, and salt until light and spreadable.
Sandwich two cookies together with the cream. Smile smugly.
Serve immediately or chill them if you somehow have restraint.