Start by letting your salted butter soften on the counter until it feels pliable but not melty, then beat it with the brown sugar until the mixture turns light and airy. Once it looks smooth and creamy, mix in the egg and vanilla, stirring until everything blends together into a silky base.
In another bowl, whisk the flour with the baking soda, then add it slowly into the wet mixture. Mix only until the dough forms, stopping early keeps the cookies soft instead of tough. Stir in the mini chocolate chips, and if you want a little extra chocolate depth, sprinkle in a tiny pinch of espresso powder. It’s subtle but makes the flavor richer.
Cover the dough and let it chill in the fridge for about 20 minutes so it firms up and holds its shape while baking. When the dough is ready, dust your surface with a little flour and roll it out to roughly ½ inch thick. Press out your heart shapes with a cookie cutter, gathering the scraps and rolling them out again until you’ve used up all the dough.
Preheat the oven to 350°F, line a baking sheet with parchment, and arrange the cutouts with a bit of space between each one. Bake them for 9–11 minutes, just until the edges start turning lightly golden and the centers stay soft. If any cookies spread a bit, don’t worry, you can still clearly see the heart shape and that slightly rustic look is part of the charm! But if you’d like them to look extra neat and perfect, gently press the cutter over the cookies while they’re still warm to clean up the edges.
Let the cookies sit on the baking sheet for a few minutes before moving them to a cooling rack. Once they’ve cooled slightly, enjoy their chewy centers, chocolatey pockets, and perfect heart-shaped charm.