Slice your pre-cooked bratwurst into bite-sized rounds, about half an inch thick. If they're cold from the fridge, give them a quick warm-up in a skillet for a couple of minutes. Set them aside on a plate while you prep everything else.
Cut your hard cheese into thin, even slices so they fold or fan out nicely on the board. Slice your honeycrisp apple into thin wedges and pat them dry with a paper towel to keep browning at bay.
Spoon the sauerkraut, whole grain mustard, and cornichons into their own small bowls. This keeps everything tidy and stops the wetter ingredients from soaking into your pretzels or cheese.
Start by placing your bowls of sauerkraut, mustard, and cornichons at different points on the board so the flavors are spread out. Then layer in your cheeses, bratwurst rounds, and pretzel bites around them.
Tuck the blackberries and apple slices into any open spaces on the board for color and freshness. Add the pretzel rods standing upright or leaning against a bowl for a bit of height and visual interest.
Give the cheese and sauerkraut a light dusting of ground pepper right before serving. Set the board out immediately so the pretzels stay soft and the cheese doesn't dry out.