7 tablespoons unsalted butter, kept very cold and cut into chunks
3/4 cup all-purpose flour, plus
1 tablespoon all-purpose flour
1 pinch salt, a good large pinch
1/2 teaspoon mustard powder
1/2 cup coarsely grated aged cheddar cheese
1/2 cup finely grated parmesan cheese
1 -2 tablespoon nigella seeds (black onion seeds)
1 egg yolk, beaten
Directions:
1. Combine all ingredients in a food processor. Pulse until ingredients come together in a loose ball. Turn out onto plastic wrap. Work the mass together with the tips of your fingers until blended. Form into a log and wrap tightly. Chill in refrigerator at least 30 minutes, up to overnight. 2. Preheat oven to 350°F Line a baking sheet with parchment or Silpat. 3. Dip the tip of a knife into a mug of very hot water, then cut thin slices off the log. Place on baking sheet about 1 apart. Bake 10 minutes or until golden and crisp. Remove to a rack to cool.
