Preheat the oven to 375°F (190°C). In a bowl, whisk together the flour, salt, and cayenne. In a food processor, combine the butter and cheese and process until a smooth paste forms. Add the flour mixture and pulse several times until a ragged dough forms. Remove the
dough from the processor and shape it into a smooth ball.
To make rustic crackers, pinch off nuggets of the dough and shape between your palms into 1-inch (2.5-cm) balls. On a lightly floured work surface, roll out each ball into a round about ⅛ inch (3 mm) thick. To make more refined crackers, on a lightly floured surface, roll out the large dough ball into a sheet ⅛ inch thick. Using a pastry cutter about 1½ inches (4 cm) in diameter, cut out rounds. Gather up the dough scraps, reroll, and cut out more rounds.
Using a spatula, carefully transfer the dough rounds to one or more ungreased rimmed baking sheets, spacing them about ½ inch (12 mm) apart. In a small bowl, stir together the caraway, poppy, and cumin seeds. Scatter the mixed seeds evenly over the crackers, then gently press them into the dough. Bake until crisp and lightly golden, 12–15 minutes. Let cool for at least 10 minutes on the baking sheet(s) on a wire rack, then serve warm or at room temperature.