Combine the Manchego, flour, and butter in a food processor. Pulse just until the dough comes together. Add the pecans and pulse until incorporated. Transfer the dough to a piece of plastic wrap and form it into a log 1½ to 2 inches in diameter. Chill until firm, at least 2 hours or up to 2 days.
Heat the oven to 325ºF. Grease two baking sheets. Slice the log into coins about ¼ inch thick and place them an inch apart on the prepared sheets. Bake, rotating the pans once, until the crackers are firm to the touch but not browned, 12 to 14 minutes. Remove the baking sheets from the oven and raise the oven temperature to 500ºF. When the oven reaches 500ºF, about 10 minutes later, return the sheets to the oven and bake until the crackers are golden brown, 3 to 4 minutes. Remove the crackers from the oven and immediately sprinkle them with the salt and paprika. Remove the crackers to racks to cool completely.
Tip: You can replace the pecans with almonds.