These can't-stop-at-one healthy crackers are like cheesy shortbread cookies. The texture is slightly crisp on the edges and a bit tender in the center.
Place Boursin in the bowl of a stand mixer fitted with a paddle attachment. Add Parmesan, butter, salt and pepper and beat just to combine. Add egg and chives; beat to combine. Add all-purpose flour and whole-wheat flour and mix at low speed, adding more all-purpose flour, 1 tablespoon at a time, until a cohesive dough forms (it should have the feel of soft Play-Doh).
Divide the dough in half and shape each piece into a 6-inch log, 1 1/2 inches in diameter. Wrap the logs tightly in plastic wrap and freeze until firm, about 1 hour, or refrigerate for up to 3 days.
Preheat oven to 400 degrees F. Line 2 baking sheets with parchment paper.
Spread a layer of seeds or nuts, if using, on a rimmed baking sheet. Roll the chilled logs firmly in the seeds to coat. Slice into even 1/8- to 1/4-inch-thick slices. Arrange about 1 inch apart on the prepared baking sheets.
Bake one pan of crackers at a time, rotating the pan halfway, until light golden around the edges and browned on the bottom, 12 to 16 minutes. Let cool completely on the pan on a wire rack, about 20 minutes.
To make ahead: Refrigerate dough logs (Steps 1-2) for up to 3 days. Store crackers airtight at room temperature for up to 1 week or freeze for up to 3 months.
Equipment: Parchment paper