Made Mexican Bun with chocolate coffee topping the other day. I used coffee emulco & some instant coffee and found that I couldn't taste the coffee flavor. Perhaps the cocoa powder was over powering the flavor of coffee? Still need to experiment more with the topping. But here's the chocolate topping recipe.
Chocolate Flavor Topping
1/3 cup sifted cake flour
1/4 cup sifted icing sugar
1/2 stick of soften butter (or 1/4 cup)
2 Tbp. Hersey cocoa powder
Combine all ingredients in a bowl. Whisk until all blended and put it into a piping bag and pipe spiral on top of each bun. Bake in 375'F for 8-10 mins.
For the buns:
Use any basic sweet bun recipe. The filling will be salted butter straight from the fridge. Cut into cube to use as filling, about 1/2 Tbp. for each bun.