Step 1

In a food processor fitted with the blade attachment, add the butter and cream cheese. Process until fully combined. Add the cheese, milk and mustard powders. Process again until smooth, 30 seconds to 1 minute, scraping down the sides with a rubber spatula as needed.

Step 2

Transfer to a piping bag fitted with a small star tip. Pipe onto the crackers and serve immediately. Can be made a few days ahead and stored in the refrigerator, but let sit on the counter until it’s soft enough to put into the piping bag before using.