Pulse both flours, the oats, brown sugar and fine salt in a food processor until combined. Add the butter and pulse until the mixture looks like wet sand. Add the peanuts, peanut butter and milk and pulse until the mixture clumps together. Turn the dough out onto a lightly floured surface, form into a ball and knead 4 or 5 times. Roll into a 12-inch-long log, about 1 inch in diameter. Wrap in plastic wrap and refrigerate until firm, about 2 hours. Preheat the oven to 375 degrees F and line 2 baking sheets with parchment paper. Slice the dough into 1/4 -inch-thick rounds and arrange 1 inch apart on the prepared baking sheets. Bake until golden, 10 to 12 minutes. Transfer the baking sheets to racks and let the crackers cool.
Meanwhile, make the glazed grapes: Cook the granulated sugar, wine and thyme in a small saucepan over medium heat until syrupy, 10 to 12 minutes. Discard the thyme and add the grapes and kosher salt; stir to coat and cook 1 more minute. Remove from the heat and let cool. Spread each cracker with cheese and top with a glazed grape. Season with pepper, if desired. Photograph by Kana Okada