Cheese and Onion Scrumps

• 7 tablespoons unsalted butter, kept very cold and cut into chunks
• 34 cup all-purpose flour, plus
• 1 tablespoon all-purpose flour
• 1 pinch salt, a good large pinch
• 12 teaspoon mustard powder
• 12 cup coarsely grated aged cheddar cheese
• 12 cup finely grated parmesan cheese
• 1 -2 tablespoon nigella seeds (black onion seeds)
• 1 egg yolk, beaten

1. Combine all ingredients in a food processor.
2. Pulse until ingredients come together in a loose ball.
3. Turn out onto plastic wrap.
4. Work the mass together with the tips of your fingers until blended.
5. Form into a log and wrap tightly.
6. Chill in refrigerator at least 30 minutes, up to overnight.
7. Preheat oven to 350F Line a baking sheet with parchment or Silpat.
8. Dip the tip of a knife into a mug of very hot water, then cut thin slices off the log.
9. Place on baking sheet about 1" apart.
10. Bake 10 minutes or until golden and crisp.
11. Remove to a rack to cool.

unsalted butter, flour, flour, salt, mustard powder, cheddar cheese, parmesan cheese, nigella seeds, egg yolk

Taken from www.food.com/recipe/cheese-and-onion-scrumps-347434 (may not work)