Preheat a large skillet or griddle over medium heat.
In a medium bowl, whisk together 1 cup flour, 2 Tbsp. sugar, 1 tsp baking powder, ½ tsp baking soda, and ¼ tsp salt.
In a small bowl, whisk together 1 ¼ cup buttermilk, 1 beaten egg, and ⅓ cup creamy peanut butter until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined; the batter should be slightly lumpy. Do not overmix.
Lightly spray or grease the preheated skillet. Use a ¼-cup measure to portion batter onto the skillet for each pancake. Because the batter is thick, gently spread each mound with the back of a spoon, spatula, or the measuring cup to form a round pancake.
Immediately sprinkle a few pieces of the ½ cup chopped mini chocolate peanut butter cups onto each uncooked pancake. Use a spoon to cover the candy pieces with a little batter so they adhere.
Cook until bubbles form on the surface and the edges look set, about 2–3 minutes. Flip and cook the other side until golden and cooked through, about 1–2 minutes more.
Transfer cooked pancakes to a plate and keep warm while you repeat with the remaining batter; re-spray the skillet as needed between batches.
Serve the pancakes topped with whipped cream, chocolate syrup, and any remaining chopped peanut butter cups.