In a large skillet, stir the cornmeal over moderate heat, shaking the pan occasionally, until lightly toasted, about 2 minutes. Transfer to a plate to cool.
In a medium bowl, combine the cornmeal with the flour, 1/2 cup of the pumpkin seeds, the salt, sugar and crushed red pepper. Using your fingers, work the butter into the cornmeal mixture until incorporated. Mix in the milk, pressing the dough with your hands to form a ball; add a little more milk if necessary. Cover the dough and refrigerate until chilled and firm, about 1 hour.
Preheat the oven to 350°. Butter 2 baking sheets. Pinch off 1-inch pieces of dough and roll into balls. Arrange the balls on the baking sheet and press into 2-inch rounds with a flat-bottomed glass. Press the remaining 1/4 cup of pumpkin seeds into the rounds. Bake the crackers for about 10 minutes, or until browned around the edges. Let cool for 5 minutes, then transfer to a large plate. Serve warm or at room temperature.
The cracker dough can be frozen for up to 1 month. The crackers can be stored overnight in an airtight container. Recrisp them in a 300° oven for a few minutes before serving.