Preheat oven to 325°F and line a 12-cup muffin tin with paper liners.
Mix crumbs, 3 tbsp sugar, and melted butter; press 1 tbsp into each liner for the crust.
Beat cream cheese and 1/2 cup sugar until smooth, then add egg, sour cream, espresso mixture, vanilla, and salt.
Spoon filling over crusts, filling each about 3/4 full.
Bake 15–18 minutes until centers are set but still slightly jiggly.
Cool in tin 10 minutes, then transfer to rack. Chill at least 2 hours before serving; dust with cocoa or shave chocolate if desired.