I recently used this one. It actually called for mascarpone, but I only had cream cheese on hand. I made it plain, then added the espresso powder to half (for chocolate cupcakes) and left the othe half plain cream cheese (for strawberry cupcakes). It has a thin consistency, but I han no problems while filling the cc. You may add more sugar if needed.
Espresso-Cream Cheese Filling (24-30 cupcakes)
8 ounces cream cheese
2 tbsp milk
1/2 tsp vanilla extract
2 tsp finely ground espresso beans or espresso powder
2 cups confectioners' sugar, sifted
In the bowl of a stand mixer, beat the cream cheese, milk, vanilla and espresso until fluffy. On low speed, slowly beat in the sugar until smooth. Transfer filling to a pastry bag fitted with a 1/4-inch plain tip. Insert tip into the top center of cooled cupcake and dispense about 2 tsp filling into the cupcake.