Ingredients
1/2 cup (1 stick) unsalted butter, room temperature
1/2 pound sharp cheddar, grated (3 cups)
1 large egg
1 teaspoon Dijon mustard
1 teaspoon fine salt
3/4 teaspoon red-pepper flakes
1 1/4 cups all-purpose flour (spooned and leveled)
Preparation
In a food processor, pulse together butter, cheese, egg, mustard, salt, and red-pepper flakes until smooth. Add flour and pulse until combined. Transfer dough to a work surface and form into a 2-inch-wide log. Wrap in plastic and refrigerate until firm, 4 hours (or up to 1 day).
Preheat oven to 350 degrees, with racks in upper and lower thirds. Slice dough into 1/4-inch rounds and arrange, 1 inch apart, on 2 parchment-lined baking sheets. Bake until edges are golden, 15 to 20 minutes, rotating sheets halfway through. Let cool completely on racks before serving.
