In a large mixing bowl, combine all-purpose flour, grated cheese, salt, garlic powder, and cayenne pepper. Stir well with a whisk until evenly blended.

Cut cubed cold butter into the flour mixture using a pastry cutter or your fingertips. Work until the mixture resembles coarse breadcrumbs.

Gradually add ice-cold water, mixing gently until the dough comes together. If it's too crumbly, add more water until it forms a soft ball.

Shape the dough into a flat disk, wrap it tightly in plastic wrap, and refrigerate for at least 1 hour.

Preheat your oven to 375°F (190°C). Roll the chilled dough on a lightly floured surface to 1/8 inch thickness. Cut into squares.

Transfer the squares onto parchment-lined baking sheets. Brush with an egg wash, sprinkle with salt, and bake for 12-15 minutes until golden brown.