Preheat the oven to 325 F and line a baking sheet with parchment paper.

In a large bowl using an electric mixer, beat the butter and sugar together on high until light and fluffy, 2-3 minutes. Add the vanilla and beat until well incorporated.

Add the flour, cornstarch, instant espresso powder, and salt and beat to combine for 1-2 minutes. The mixture will still look powdery.

Using your hands, press (almost kneading here) the dough together for about 5 minutes, until the mixture holds together as a smooth ball of dough.

Separate the dough into two pieces and roll out each ball of dough on a lightly floured surface with a rolling pin to approximately 1/4" thickness. Cut into shapes using a cookie cutter (we used a 2.5" round cookie cutter).

Place the cookies on the prepared baking sheet, leaving 1-2" between each cookie, and bake for around 12 minutes, until light golden brown around the edges. Transfer the cookies to a cooling rack to cool completely and repeat with the remaining dough (the scraps can be re-rolled).

Melt the chocolate and coconut oil together in the microwave in 30 second intervals, stirring each time. Lightly drizzle the melted chocolate on top of the cookies and place on a cooling rack (to set the chocolate faster, pop the cookies in the freezer for 5-10 minutes). Store the cookies at room temperature or in the fridge for up to 1 week or in the freezer for up to 1 month.