Step #1 Toast hazelnuts in a 10- by 15-inch baking pan in a 350° regular or convection oven until golden beneath skins, 7 to 10 mins.
Step #2 Pour onto a clean linen towel.
Step #3 When nuts are cool enough to handle, rub in towel to remove loose skins.
Step #4 Whirl hazelnuts in a food processor/blender until finely sliced, or finely chop with a knife; you should have 1 1/4 c.
Step #5 Reserve 1/4 c to sprinkle it over cooked pancakes.
Step #6 In a bowl, mix all-purpose flour, baking powder, sugar, whole-wheat flour, baking soda, cinnamon, & salt.
Step #7 In a small bowl, buttermilk, whisk eggs, & butter until mixed.
Step #8 Stir egg mixture into flour mixture until evenly moistened, then carefully stir in the remaining 1 c hazelnuts.
Step #9 Place a nonstick griddle or a 12-inch nonstick frying pan over med-heat/flame (350°).
Step #10 When hot, coat lightly with oil & adjust heat to maintain temperature.
Step #11 Spoon batter in 1/3-c portions onto griddle & cook this until pancakes are browned on the bottom & edges begin to look dry, about 2 mins; turn with a wide spatula & brown other sides, 1 1/2 to 2 mins longer.
Step #12 Coat pan with more oil as necessary to cook remaining pancakes.
Step #13 Serve pancakes as cooked or keep warm in a single layer on baking sheets in a 200° oven for up to 15 mins.