Preheat oven to 325°F (165°C).
Line a baking sheet with parchment paper.
In a mixing bowl, cream the grated cheese until soft and slightly paste-like.
Add cold butter and mustard (and any optional ingredients). Mix by hand with a spatula or fork until the mixture is combined but not airy.
Avoid electric mixers — they add too much air and can make the texture cakey.
Add flour gradually, mixing until the dough is smooth, flexible, and spreadable — but still firm enough to hold its shape.
You may not need the full 1 cup. Start with ¾ cup and adjust as needed.
Scoop the dough into a piping bag with a star tip (or use a ziplock with the corner snipped).
Pipe into straws, small logs, or decorative swirls on your baking sheet.
Bake for 15–20 minutes, or until the bottom edges are just turning golden brown.
For crispier straws, bake closer to 18–20 minutes.
Let cool for 5–10 minutes. Enjoy warm or at room temp.